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id	title	slug	type	status	content	archieml	archieml_update_statistics	published_at	updated_at	gdocSuccessorId	authors	excerpt	created_at_in_wordpress	updated_at_in_wordpress	featured_image	formattingOptions	markdown	wpApiSnapshot
30197	The Spanish flu: The global impact of the largest influenza pandemic in history	spanish-flu-largest-influenza-pandemic-in-history	post	publish	<!-- wp:html --> <div class="blog-info">Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article — mostly the mortality estimates of the various influenza pandemics — were revised in May 2023.</div> <!-- /wp:html --> <!-- wp:paragraph --> <p>In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy, which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy <a href="https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time">has doubled</a> in all regions of the world.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the ‘Spanish flu’.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. <em>Period life expectancy</em>, which is the precise name for this measure, captures the mortality in <em>one particular year</em>. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year’s mortality pattern would remain constant throughout their entire lifetimes.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>This influenza outbreak wasn’t restricted to Spain and it didn’t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. <a href="https://doi.org/10.1073/pnas.1324197111">https://doi.org/10.1073/pnas.1324197111<br></a>Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. <a href="https://doi.org/10.1186/1479-5876-2-3">https://doi.org/10.1186/1479-5876-2-3</a> {/ref} </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>But it <a href="https://www.history.com/news/why-was-it-called-the-spanish-flu">was named</a> as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC <a href="https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html">here</a>.{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) – Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications: </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>McLane, J. R. (2013). <a href="https://sites.otago.ac.nz/Sites/article/view/215">Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies</a>, 10(2), 30-51.<a href="https://sites.otago.ac.nz/Sites/article/view/215"> </a></p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:html --> <iframe src="https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA" style="width: 100%; height: 600px; border: 0px none;"></iframe> <!-- /wp:html --> <!-- wp:heading {"level":4} --> <h4>How many people died in the Spanish flu pandemic?</h4> <!-- /wp:heading --> <!-- wp:heading {"level":5} --> <h5>The global death count of the flu today:</h5> <!-- /wp:heading --> <!-- wp:paragraph --> <p>To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an “average of 389 000 (uncertainty range 294 000-518 000) respiratory deaths were associated with influenza globally each year”.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) – Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/">here</a>.{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today’s baseline. </p> <!-- /wp:paragraph --> <!-- wp:heading {"level":5} --> <h5>Global deaths of the Spanish flu</h5> <!-- /wp:heading --> <!-- wp:paragraph --> <p>Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: <em>Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.</em></p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Johnson, N.P. and Mueller, J. (2002) – Updating the accounts: global mortality of the 1918-1920 “Spanish" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online <a href="https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents">here</a>.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Patterson, K.D. and Pyle, G.F. (1991) – The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online <a href="https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). "Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic". American Journal of Epidemiology. 187 (12): 2561–2567. doi:10.1093/aje/kwy191. PMID 30202996. Online <a href="https://academic.oup.com/aje/article/187/12/2561/5092383">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:heading {"level":5} --> <h5>The global death rate of the Spanish flu</h5> <!-- /wp:heading --> <!-- wp:paragraph --> <p>How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p><a href="https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time">Estimates</a> suggest that the world population in 1918 was 1.8 billion. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)100=0.95{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher – 100 million as these authors suggest – then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref} </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like <a href="https://ourworldindata.org/grapher/population?country=OWID_WRL">this one</a>) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:heading {"level":5} --> <h5>Other large influenza pandemics</h5> <!-- /wp:heading --> <!-- wp:paragraph --> <p>The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) – A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918–1919. BMC Infect Dis 19, 117 (2019). <a href="https://doi.org/10.1186/s12879-019-3750-8">https://doi.org/10.1186/s12879-019-3750-8</a> </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Estimates for the death toll of the “Asian Flu” (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The same authors estimate that the “Hong Kong Flu” (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The “Russian Flu” pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. <a href="https://doi.org/10.1073/pnas.1324197111">https://doi.org/10.1073/pnas.1324197111</a> {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The “Swine flu” pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., … Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687–695. <a href="https://doi.org/10.1016/S1473-3099(12)70121-4">https://doi.org/10.1016/S1473-3099(12)70121-4</a> </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. <a href="https://doi.org/10.1371/journal.pmed.1001558">https://doi.org/10.1371/journal.pmed.1001558</a> </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.</p> <!-- /wp:paragraph --> <!-- wp:image {"id":57012,"sizeSlug":"full","linkDestination":"none"} --> <figure class="wp-block-image size-full"><img src="https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png" alt="" class="wp-image-57012"/></figure> <!-- /wp:image --> <!-- wp:heading {"level":4} --> <h4>The impact of the Spanish flu on different age groups</h4> <!-- /wp:heading --> <!-- wp:paragraph --> <p>This last visualization here shows the life expectancy in England and Wales by age. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy ‘only’ increased because child mortality declined is <a href="https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age">not true</a>.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both <a href="https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017">lower respiratory infections (pneumonia)</a> and <a href="https://ourworldindata.org/grapher/death-rate-upper-respiratory-age">upper respiratory infections</a> today, death rates are highest for those who are 70 years and older. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>This data tells us that young people <a href="https://ourworldindata.org/age-structure">accounted for a large share</a> of the deaths, this made this pandemic especially devastating.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak – the already discussed <a href="https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic">‘Russian flu pandemic’</a> of 1889–90 – which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) – Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/">here</a>.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:image {"id":30185,"sizeSlug":"full"} --> <figure class="wp-block-image size-full"><img src="https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png" alt="" class="wp-image-30185"/></figure> <!-- /wp:image --> <!-- wp:heading {"level":4} --> <h4>How the Spanish flu differs from the Coronavirus outbreak in 2020</h4> <!-- /wp:heading --> <!-- wp:paragraph --> <p>Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>The age-specific mortality seems to be very different. As we’ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) – The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online <a href="https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>We’ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary <em>bacterial</em> infections. Morens et al (2008) found that during the Spanish flu “the majority of deaths … likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.”{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) – Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962–970. 10.1086/591708. Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share <a href="https://ourworldindata.org/extreme-history-methods">was extremely poor</a> – large shares of the population were undernourished, in most parts of the world the populations lived <a href="https://ourworldindata.org/life-expectancy-globally">in very poor health</a>, and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent <a href="https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run">large shares</a> of their resources on the war. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>While most of the world is <a href="https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts">much richer and healthier now</a>, the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Boëlle, Eric D’Ortenzio, et al. (2020) – “Preparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.” <em>The Lancet</em> (February 20, 2020).<a href="https://doi.org/10.1016/S0140-6736(20)30411-6"> https://doi.org/10.1016/S0140-6736(20)30411-6</a>.</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>See also</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) – Effects of Response to 2014–2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433–441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667">here</a>.{/ref}</p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago. </p> <!-- /wp:paragraph --> <!-- wp:paragraph --> <p>But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response – WHO guidance document. Published in 2009 by the WHO. Online <a href="https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf">here</a>.Roman Duda (2016) – Problem profile: Biorisk reduction. Published by 80,000 hours. Online <a href="https://80000hours.org/problem-profiles/biosecurity/">here</a>.{/ref}</p> <!-- /wp:paragraph -->	{ "id": "wp-30197", "slug": "spanish-flu-largest-influenza-pandemic-in-history", "content": { "toc": [], "body": [ { "type": "text", "value": [ { "text": "Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article \u2014 mostly the mortality estimates of the various influenza pandemics \u2014 were revised in May 2023.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy,\u00a0which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time", "children": [ { "text": "has doubled", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " in all regions of the world.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the \u2018Spanish flu\u2019.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. ", "spanType": "span-simple-text" }, { "children": [ { "text": "Period life expectancy", "spanType": "span-simple-text" } ], "spanType": "span-italic" }, { "text": ", which is the precise name for this measure, captures the mortality in ", "spanType": "span-simple-text" }, { "children": [ { "text": "one particular year", "spanType": "span-simple-text" } ], "spanType": "span-italic" }, { "text": ". It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year\u2019s mortality pattern would remain constant throughout their entire lifetimes.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "This influenza outbreak wasn\u2019t restricted to Spain and it didn\u2019t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1073/pnas.1324197111", "children": [ { "text": "https://doi.org/10.1073/pnas.1324197111", "spanType": "span-simple-text" }, { "spanType": "span-newline" } ], "spanType": "span-link" }, { "text": "Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1186/1479-5876-2-3", "children": [ { "text": "https://doi.org/10.1186/1479-5876-2-3", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref}\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "But it ", "spanType": "span-simple-text" }, { "url": "https://www.history.com/news/why-was-it-called-the-spanish-flu", "children": [ { "text": "was named", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC ", "spanType": "span-simple-text" }, { "url": "https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) \u2013 Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications:\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "McLane, J. R. (2013). ", "spanType": "span-simple-text" }, { "url": "https://sites.otago.ac.nz/Sites/article/view/215", "children": [ { "text": "Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ", 10(2), 30-51.", "spanType": "span-simple-text" }, { "url": "https://sites.otago.ac.nz/Sites/article/view/215", "children": [ { "text": "\u00a0", "spanType": "span-simple-text" } ], "spanType": "span-link" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "url": "https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA", "type": "chart", "parseErrors": [] }, { "text": [ { "text": "How many people died in the Spanish flu pandemic?", "spanType": "span-simple-text" } ], "type": "heading", "level": 2, "parseErrors": [] }, { "text": [ { "text": "The global death count of the flu today:", "spanType": "span-simple-text" } ], "type": "heading", "level": 3, "parseErrors": [] }, { "type": "text", "value": [ { "text": "To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an \u201caverage of 389\u2009000 (uncertainty range 294\u2009000-518\u2009000) respiratory deaths were associated with influenza globally each year\u201d.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) \u2013 Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online ", "spanType": "span-simple-text" }, { "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today\u2019s baseline.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "text": [ { "text": "Global deaths of the Spanish flu", "spanType": "span-simple-text" } ], "type": "heading", "level": 3, "parseErrors": [] }, { "type": "text", "value": [ { "text": "Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: ", "spanType": "span-simple-text" }, { "children": [ { "text": "Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.", "spanType": "span-simple-text" } ], "spanType": "span-italic" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Johnson, N.P. and Mueller, J. (2002) \u2013 Updating the accounts: global mortality of the 1918-1920 \u201cSpanish\" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online ", "spanType": "span-simple-text" }, { "url": "https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Patterson, K.D. and Pyle, G.F. (1991) \u2013 The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online ", "spanType": "span-simple-text" }, { "url": "https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). \"Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic\". American Journal of Epidemiology. 187 (12): 2561\u20132567. doi:10.1093/aje/kwy191. PMID 30202996. Online ", "spanType": "span-simple-text" }, { "url": "https://academic.oup.com/aje/article/187/12/2561/5092383", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "text": [ { "text": "The global death rate of the Spanish flu", "spanType": "span-simple-text" } ], "type": "heading", "level": 3, "parseErrors": [] }, { "type": "text", "value": [ { "text": "How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "url": "https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time", "children": [ { "text": "Estimates", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " suggest that the world population in 1918 was 1.8 billion.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)100=0.95{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher\u00a0\u2013 100 million as these authors suggest \u2013 then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref}\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/grapher/population?country=OWID_WRL", "children": [ { "text": "this one", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ") this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "text": [ { "text": "Other large influenza pandemics", "spanType": "span-simple-text" } ], "type": "heading", "level": 3, "parseErrors": [] }, { "type": "text", "value": [ { "text": "The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) \u2013 A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918\u20131919. BMC Infect Dis 19, 117 (2019). ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1186/s12879-019-3750-8", "children": [ { "text": "https://doi.org/10.1186/s12879-019-3750-8", "spanType": "span-simple-text" } ], "spanType": "span-link" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ", "spanType": "span-simple-text" }, { "url": "https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Estimates for the death toll of the \u201cAsian Flu\u201d (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1093/aje/kwy191", "children": [ { "text": "https://doi.org/10.1093/aje/kwy191", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The same authors estimate that the \u201cHong Kong Flu\u201d (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1093/aje/kwy191", "children": [ { "text": "https://doi.org/10.1093/aje/kwy191", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The \u201cRussian Flu\u201d pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1073/pnas.1324197111", "children": [ { "text": "https://doi.org/10.1073/pnas.1324197111", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1093/aje/kwy191", "children": [ { "text": "https://doi.org/10.1093/aje/kwy191", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The \u201cSwine flu\u201d pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., \u2026 Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687\u2013695. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1016/S1473-3099(12)70121-4", "children": [ { "text": "https://doi.org/10.1016/S1473-3099(12)70121-4", "spanType": "span-simple-text" } ], "spanType": "span-link" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1371/journal.pmed.1001558", "children": [ { "text": "https://doi.org/10.1371/journal.pmed.1001558", "spanType": "span-simple-text" } ], "spanType": "span-link" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1093/aje/kwy191", "children": [ { "text": "https://doi.org/10.1093/aje/kwy191", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " {/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "alt": "", "size": "wide", "type": "image", "filename": "Influenza-pandemics-in-comparison-1.png", "parseErrors": [] }, { "text": [ { "text": "The impact of the Spanish flu on different age groups", "spanType": "span-simple-text" } ], "type": "heading", "level": 2, "parseErrors": [] }, { "type": "text", "value": [ { "text": "This last visualization here shows the life expectancy in England and Wales by age.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy \u2018only\u2019 increased because child mortality declined is ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age", "children": [ { "text": "not true", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017", "children": [ { "text": "lower respiratory infections (pneumonia)", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " and ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/grapher/death-rate-upper-respiratory-age", "children": [ { "text": "upper respiratory infections", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " today, death rates are highest for those who are 70 years and older.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "This data tells us that young people ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/age-structure", "children": [ { "text": "accounted for a large share", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " of the deaths, this made this pandemic especially devastating.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak \u2013 the already discussed ", "spanType": "span-simple-text" }, { "url": "https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic", "children": [ { "text": "\u2018Russian flu pandemic\u2019", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " of 1889\u201390 \u2013 which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) \u2013 Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online ", "spanType": "span-simple-text" }, { "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ", "spanType": "span-simple-text" }, { "url": "https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ", "spanType": "span-simple-text" }, { "url": "https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "alt": "", "size": "wide", "type": "image", "filename": "Life-expectancy-by-age-in-the-UK-1700-to-2013.png", "parseErrors": [] }, { "text": [ { "text": "How the Spanish flu differs from the Coronavirus outbreak in 2020", "spanType": "span-simple-text" } ], "type": "heading", "level": 2, "parseErrors": [] }, { "type": "text", "value": [ { "text": "Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "The age-specific mortality seems to be very different. As we\u2019ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) \u2013 The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online ", "spanType": "span-simple-text" }, { "url": "https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "We\u2019ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary ", "spanType": "span-simple-text" }, { "children": [ { "text": "bacterial", "spanType": "span-simple-text" } ], "spanType": "span-italic" }, { "text": " infections. Morens et al (2008) found that during the Spanish flu \u201cthe majority of deaths \u2026 likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory\u2013tract bacteria.\u201d{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) \u2013 Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962\u2013970. 10.1086/591708. Online ", "spanType": "span-simple-text" }, { "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/extreme-history-methods", "children": [ { "text": "was extremely poor", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " \u2013 large shares of the population were undernourished, in most parts of the world the populations lived ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/life-expectancy-globally", "children": [ { "text": "in very poor health", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ", and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run", "children": [ { "text": "large shares", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": " of their resources on the war.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "While most of the world is ", "spanType": "span-simple-text" }, { "url": "https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts", "children": [ { "text": "much richer and healthier now", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ", the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Bo\u00eblle, Eric D\u2019Ortenzio, et al. (2020) \u2013 \u201cPreparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.\u201d ", "spanType": "span-simple-text" }, { "children": [ { "text": "The Lancet", "spanType": "span-simple-text" } ], "spanType": "span-italic" }, { "text": " (February 20, 2020).", "spanType": "span-simple-text" }, { "url": "https://doi.org/10.1016/S0140-6736(20)30411-6", "children": [ { "text": " https://doi.org/10.1016/S0140-6736(20)30411-6", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "See also", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) \u2013 Effects of Response to 2014\u20132015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433\u2013441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online ", "spanType": "span-simple-text" }, { "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago.\u00a0", "spanType": "span-simple-text" } ], "parseErrors": [] }, { "type": "text", "value": [ { "text": "But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response \u2013 WHO guidance document. Published in 2009 by the WHO. Online ", "spanType": "span-simple-text" }, { "url": "https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".Roman Duda (2016) \u2013 Problem profile: Biorisk reduction. Published by 80,000 hours. Online ", "spanType": "span-simple-text" }, { "url": "https://80000hours.org/problem-profiles/biosecurity/", "children": [ { "text": "here", "spanType": "span-simple-text" } ], "spanType": "span-link" }, { "text": ".{/ref}", "spanType": "span-simple-text" } ], "parseErrors": [] } ], "type": "article", "title": "The Spanish flu: The global impact of the largest influenza pandemic in history", "authors": [ "Max Roser" ], "dateline": "March 4, 2020", "sidebar-toc": false, "featured-image": "Screenshot-2022-03-14-at-11.51.27.png" }, "createdAt": "2020-03-04T10:23:17.000Z", "published": false, "updatedAt": "2023-05-17T21:16:43.000Z", "revisionId": null, "publishedAt": "2020-03-04T10:23:59.000Z", "relatedCharts": [], "publicationContext": "listed" }	{ "errors": [ { "name": "unexpected wp component tag", "details": "Found unhandled wp:comment tag image" }, { "name": "unexpected wp component tag", "details": "Found unhandled wp:comment tag image" } ], "numBlocks": 69, "numErrors": 2, "wpTagCounts": { "html": 2, "image": 2, "heading": 7, "paragraph": 58 }, "htmlTagCounts": { "p": 58, "h4": 3, "h5": 4, "div": 1, "figure": 2, "iframe": 1 } }	2020-03-04 10:23:59	2024-02-16 14:22:49	1qQqo2roAI9agAMPd0wcgY3haOKflkKYunyERiYRKGpw	[ "Max Roser" ]		2020-03-04 10:23:17	2023-05-17 21:16:43	https://ourworldindata.org/wp-content/uploads/2020/03/Screenshot-2022-03-14-at-11.51.27.png	{}	Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article — mostly the mortality estimates of the various influenza pandemics — were revised in May 2023. In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy, which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy [has doubled](https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time) in all regions of the world. What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the ‘Spanish flu’. To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. _Period life expectancy_, which is the precise name for this measure, captures the mortality in _one particular year_. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year’s mortality pattern would remain constant throughout their entire lifetimes. This influenza outbreak wasn’t restricted to Spain and it didn’t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. [https://doi.org/10.1073/pnas.1324197111 ](https://doi.org/10.1073/pnas.1324197111)Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. [https://doi.org/10.1186/1479-5876-2-3](https://doi.org/10.1186/1479-5876-2-3) {/ref} But it [was named](https://www.history.com/news/why-was-it-called-the-spanish-flu) as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time. The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC [here](https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html).{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) – Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books. The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications: McLane, J. R. (2013). [Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies](https://sites.otago.ac.nz/Sites/article/view/215), 10(2), 30-51.[ ](https://sites.otago.ac.nz/Sites/article/view/215) Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref} <Chart url="https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA"/> ## How many people died in the Spanish flu pandemic? ### The global death count of the flu today: To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an “average of 389 000 (uncertainty range 294 000-518 000) respiratory deaths were associated with influenza globally each year”. John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) – Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/).{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today’s baseline. ### Global deaths of the Spanish flu Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu. The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide. The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: _Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated._ Johnson, N.P. and Mueller, J. (2002) – Updating the accounts: global mortality of the 1918-1920 “Spanish" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online [here](https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents). The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref} Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths. Patterson, K.D. and Pyle, G.F. (1991) – The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online [here](https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf).{/ref} The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). "Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic". American Journal of Epidemiology. 187 (12): 2561–2567. doi:10.1093/aje/kwy191. PMID 30202996. Online [here](https://academic.oup.com/aje/article/187/12/2561/5092383).{/ref} ### The global death rate of the Spanish flu How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic? [Estimates](https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time) suggest that the world population in 1918 was 1.8 billion. Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)100=0.95{/ref} The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher – 100 million as these authors suggest – then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref} The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like [this one](https://ourworldindata.org/grapher/population?country=OWID_WRL)) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past. Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates. In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref} ### Other large influenza pandemics The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic. Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) – A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918–1919. BMC Infect Dis 19, 117 (2019). [https://doi.org/10.1186/s12879-019-3750-8](https://doi.org/10.1186/s12879-019-3750-8) According to Smith (1995) 132,000 died in England, Wales, and Ireland alone. Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} Estimates for the death toll of the “Asian Flu” (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The same authors estimate that the “Hong Kong Flu” (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The “Russian Flu” pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. [https://doi.org/10.1073/pnas.1324197111](https://doi.org/10.1073/pnas.1324197111) {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The “Swine flu” pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., … Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687–695. [https://doi.org/10.1016/S1473-3099(12)70121-4](https://doi.org/10.1016/S1473-3099(12)70121-4) Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. [https://doi.org/10.1371/journal.pmed.1001558](https://doi.org/10.1371/journal.pmed.1001558) Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history. <Image filename="Influenza-pandemics-in-comparison-1.png" alt=""/> ## The impact of the Spanish flu on different age groups This last visualization here shows the life expectancy in England and Wales by age. The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10. It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy ‘only’ increased because child mortality declined is [not true](https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age). With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both [lower respiratory infections (pneumonia)](https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017) and [upper respiratory infections](https://ourworldindata.org/grapher/death-rate-upper-respiratory-age) today, death rates are highest for those who are 70 years and older. This data tells us that young people [accounted for a large share](https://ourworldindata.org/age-structure) of the deaths, this made this pandemic especially devastating. Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak – the already discussed [‘Russian flu pandemic’](https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic) of 1889–90 – which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) – Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/). The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland. Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} <Image filename="Life-expectancy-by-age-in-the-UK-1700-to-2013.png" alt=""/> ## How the Spanish flu differs from the Coronavirus outbreak in 2020 Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered. They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above. The age-specific mortality seems to be very different. As we’ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) – The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online [here](https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU).{/ref} We’ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past. But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time. Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary _bacterial_ infections. Morens et al (2008) found that during the Spanish flu “the majority of deaths … likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.”{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) – Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962–970. 10.1086/591708. Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/).{/ref} And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share [was extremely poor](https://ourworldindata.org/extreme-history-methods) – large shares of the population were undernourished, in most parts of the world the populations lived [in very poor health](https://ourworldindata.org/life-expectancy-globally), and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent [large shares](https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run) of their resources on the war. While most of the world is [much richer and healthier now](https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts), the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Boëlle, Eric D’Ortenzio, et al. (2020) – “Preparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.” _The Lancet_ (February 20, 2020).[ https://doi.org/10.1016/S0140-6736(20)30411-6](https://doi.org/10.1016/S0140-6736(20)30411-6). See also Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) – Effects of Response to 2014–2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433–441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667).{/ref} These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago. But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response – WHO guidance document. Published in 2009 by the WHO. Online [here](https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf).Roman Duda (2016) – Problem profile: Biorisk reduction. Published by 80,000 hours. Online [here](https://80000hours.org/problem-profiles/biosecurity/).{/ref}	{ "id": 30197, "date": "2020-03-04T10:23:59", "guid": { "rendered": "https://owid.cloud/?p=30197" }, "link": "https://owid.cloud/spanish-flu-largest-influenza-pandemic-in-history", "meta": { "owid_publication_context_meta_field": { "latest": true, "homepage": true, "immediate_newsletter": true } }, "slug": "spanish-flu-largest-influenza-pandemic-in-history", "tags": [], "type": "post", "title": { "rendered": "The Spanish flu: The global impact of the largest influenza pandemic in history" }, "_links": { "self": [ { "href": "https://owid.cloud/wp-json/wp/v2/posts/30197" } ], "about": [ { "href": "https://owid.cloud/wp-json/wp/v2/types/post" } ], "author": [ { "href": "https://owid.cloud/wp-json/wp/v2/users/2", "embeddable": true } ], "curies": [ { "href": "https://api.w.org/{rel}", "name": "wp", "templated": true } ], "replies": [ { "href": "https://owid.cloud/wp-json/wp/v2/comments?post=30197", "embeddable": true } ], "wp:term": [ { "href": "https://owid.cloud/wp-json/wp/v2/categories?post=30197", "taxonomy": "category", "embeddable": true }, { "href": "https://owid.cloud/wp-json/wp/v2/tags?post=30197", "taxonomy": "post_tag", "embeddable": true } ], "collection": [ { "href": "https://owid.cloud/wp-json/wp/v2/posts" } ], "wp:attachment": [ { "href": "https://owid.cloud/wp-json/wp/v2/media?parent=30197" } ], "version-history": [ { "href": "https://owid.cloud/wp-json/wp/v2/posts/30197/revisions", "count": 21 } ], "wp:featuredmedia": [ { "href": "https://owid.cloud/wp-json/wp/v2/media/50068", "embeddable": true } ], "predecessor-version": [ { "id": 57020, "href": "https://owid.cloud/wp-json/wp/v2/posts/30197/revisions/57020" } ] }, "author": 2, "format": "standard", "status": "publish", "sticky": false, "content": { "rendered": "\n<div class=\"blog-info\">Our World in Data presents the data and research to make progress against the world’s largest problems. Parts of the article \u2014 mostly the mortality estimates of the various influenza pandemics \u2014 were revised in May 2023.</div>\n\n\n\n<p>In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy, which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy <a href=\"https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time\">has doubled</a> in all regions of the world.</p>\n\n\n\n<p>What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the \u2018Spanish flu\u2019.</p>\n\n\n\n<p>To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. <em>Period life expectancy</em>, which is the precise name for this measure, captures the mortality in <em>one particular year</em>. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year\u2019s mortality pattern would remain constant throughout their entire lifetimes.</p>\n\n\n\n<p>This influenza outbreak wasn\u2019t restricted to Spain and it didn\u2019t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. <a href=\"https://doi.org/10.1073/pnas.1324197111\">https://doi.org/10.1073/pnas.1324197111<br></a>Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. <a href=\"https://doi.org/10.1186/1479-5876-2-3\">https://doi.org/10.1186/1479-5876-2-3</a> {/ref} </p>\n\n\n\n<p>But it <a href=\"https://www.history.com/news/why-was-it-called-the-spanish-flu\">was named</a> as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.</p>\n\n\n\n<p>The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC <a href=\"https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html\">here</a>.{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) \u2013 Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.</p>\n\n\n\n<p>The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications: </p>\n\n\n\n<p>McLane, J. R. (2013). <a href=\"https://sites.otago.ac.nz/Sites/article/view/215\">Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies</a>, 10(2), 30-51.<a href=\"https://sites.otago.ac.nz/Sites/article/view/215\"> </a></p>\n\n\n\n<p>Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}</p>\n\n\n\n<iframe src=\"https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA\" style=\"width: 100%; height: 600px; border: 0px none;\"></iframe>\n\n\n\n<h4>How many people died in the Spanish flu pandemic?</h4>\n\n\n\n<h5>The global death count of the flu today:</h5>\n\n\n\n<p>To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an \u201caverage of 389\u2009000 (uncertainty range 294\u2009000-518\u2009000) respiratory deaths were associated with influenza globally each year\u201d.</p>\n\n\n\n<p>John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) \u2013 Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/\">here</a>.{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today\u2019s baseline. </p>\n\n\n\n<h5>Global deaths of the Spanish flu</h5>\n\n\n\n<p>Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu. </p>\n\n\n\n<p>The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.</p>\n\n\n\n<p>The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: <em>Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.</em></p>\n\n\n\n<p>Johnson, N.P. and Mueller, J. (2002) \u2013 Updating the accounts: global mortality of the 1918-1920 \u201cSpanish” influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online <a href=\"https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents\">here</a>.</p>\n\n\n\n<p>The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}</p>\n\n\n\n<p>Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote ‘we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918’ and published a range from 24.7-39.3 million deaths.</p>\n\n\n\n<p>Patterson, K.D. and Pyle, G.F. (1991) \u2013 The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online <a href=\"https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf\">here</a>.{/ref}</p>\n\n\n\n<p>The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). “Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic”. American Journal of Epidemiology. 187 (12): 2561\u20132567. doi:10.1093/aje/kwy191. PMID 30202996. Online <a href=\"https://academic.oup.com/aje/article/187/12/2561/5092383\">here</a>.{/ref}</p>\n\n\n\n<h5>The global death rate of the Spanish flu</h5>\n\n\n\n<p>How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?</p>\n\n\n\n<p><a href=\"https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time\">Estimates</a> suggest that the world population in 1918 was 1.8 billion. </p>\n\n\n\n<p>Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)100=0.95{/ref}</p>\n\n\n\n<p>The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher \u2013 100 million as these authors suggest \u2013 then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref} </p>\n\n\n\n<p>The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like <a href=\"https://ourworldindata.org/grapher/population?country=OWID_WRL\">this one</a>) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.</p>\n\n\n\n<p>Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.</p>\n\n\n\n<p>In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}</p>\n\n\n\n<h5>Other large influenza pandemics</h5>\n\n\n\n<p>The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic. </p>\n\n\n\n<p>Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) \u2013 A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918\u20131919. BMC Infect Dis 19, 117 (2019). <a href=\"https://doi.org/10.1186/s12879-019-3750-8\">https://doi.org/10.1186/s12879-019-3750-8</a> </p>\n\n\n\n<p>According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.</p>\n\n\n\n<p>Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<p>Estimates for the death toll of the \u201cAsian Flu\u201d (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The same authors estimate that the \u201cHong Kong Flu\u201d (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The \u201cRussian Flu\u201d pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. <a href=\"https://doi.org/10.1073/pnas.1324197111\">https://doi.org/10.1073/pnas.1324197111</a> {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The \u201cSwine flu\u201d pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., \u2026 Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687\u2013695. <a href=\"https://doi.org/10.1016/S1473-3099(12)70121-4\">https://doi.org/10.1016/S1473-3099(12)70121-4</a> </p>\n\n\n\n<p>Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. <a href=\"https://doi.org/10.1371/journal.pmed.1001558\">https://doi.org/10.1371/journal.pmed.1001558</a> </p>\n\n\n\n<p>Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.</p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" width=\"2410\" height=\"1767\" src=\"https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png\" alt=\"\" class=\"wp-image-57012\" srcset=\"https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png 2410w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-400x293.png 400w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-750x550.png 750w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-150x110.png 150w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-768x563.png 768w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-1536x1126.png 1536w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-2048x1502.png 2048w\" sizes=\"(max-width: 2410px) 100vw, 2410px\" /></figure>\n\n\n\n<h4>The impact of the Spanish flu on different age groups</h4>\n\n\n\n<p>This last visualization here shows the life expectancy in England and Wales by age. </p>\n\n\n\n<p>The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.</p>\n\n\n\n<p>It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy \u2018only\u2019 increased because child mortality declined is <a href=\"https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age\">not true</a>.</p>\n\n\n\n<p>With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both <a href=\"https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017\">lower respiratory infections (pneumonia)</a> and <a href=\"https://ourworldindata.org/grapher/death-rate-upper-respiratory-age\">upper respiratory infections</a> today, death rates are highest for those who are 70 years and older. </p>\n\n\n\n<p>This data tells us that young people <a href=\"https://ourworldindata.org/age-structure\">accounted for a large share</a> of the deaths, this made this pandemic especially devastating.</p>\n\n\n\n<p>Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak \u2013 the already discussed <a href=\"https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic\">\u2018Russian flu pandemic\u2019</a> of 1889\u201390 \u2013 which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) \u2013 Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/\">here</a>.</p>\n\n\n\n<p>The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.</p>\n\n\n\n<p>Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<p>The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" width=\"3080\" height=\"2050\" src=\"https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png\" alt=\"\" class=\"wp-image-30185\" srcset=\"https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png 3080w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-400x266.png 400w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-800x532.png 800w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-150x100.png 150w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-768x511.png 768w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-1536x1022.png 1536w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-2048x1363.png 2048w\" sizes=\"(max-width: 3080px) 100vw, 3080px\" /></figure>\n\n\n\n<h4>How the Spanish flu differs from the Coronavirus outbreak in 2020</h4>\n\n\n\n<p>Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.</p>\n\n\n\n<p>They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.</p>\n\n\n\n<p>The age-specific mortality seems to be very different. As we\u2019ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) \u2013 The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online <a href=\"https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU\">here</a>.{/ref}</p>\n\n\n\n<p>We\u2019ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.</p>\n\n\n\n<p>But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time. </p>\n\n\n\n<p>Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary <em>bacterial</em> infections. Morens et al (2008) found that during the Spanish flu \u201cthe majority of deaths \u2026 likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory\u2013tract bacteria.\u201d{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) \u2013 Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962\u2013970. 10.1086/591708. Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/\">here</a>.{/ref}</p>\n\n\n\n<p>And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share <a href=\"https://ourworldindata.org/extreme-history-methods\">was extremely poor</a> \u2013 large shares of the population were undernourished, in most parts of the world the populations lived <a href=\"https://ourworldindata.org/life-expectancy-globally\">in very poor health</a>, and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent <a href=\"https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run\">large shares</a> of their resources on the war. </p>\n\n\n\n<p>While most of the world is <a href=\"https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts\">much richer and healthier now</a>, the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Bo\u00eblle, Eric D\u2019Ortenzio, et al. (2020) \u2013 \u201cPreparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.\u201d <em>The Lancet</em> (February 20, 2020).<a href=\"https://doi.org/10.1016/S0140-6736(20)30411-6\"> https://doi.org/10.1016/S0140-6736(20)30411-6</a>.</p>\n\n\n\n<p>See also</p>\n\n\n\n<p>Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) \u2013 Effects of Response to 2014\u20132015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433\u2013441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667\">here</a>.{/ref}</p>\n\n\n\n<p>These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago. </p>\n\n\n\n<p>But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response \u2013 WHO guidance document. Published in 2009 by the WHO. Online <a href=\"https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf\">here</a>.Roman Duda (2016) \u2013 Problem profile: Biorisk reduction. Published by 80,000 hours. Online <a href=\"https://80000hours.org/problem-profiles/biosecurity/\">here</a>.{/ref}</p>\n", "protected": false }, "excerpt": { "rendered": "", "protected": false }, "date_gmt": "2020-03-04T10:23:59", "modified": "2023-05-17T22:16:43", "template": "", "categories": [ 1 ], "ping_status": "closed", "authors_name": [ "Max Roser" ], "modified_gmt": "2023-05-17T21:16:43", "comment_status": "closed", "featured_media": 50068, "featured_media_paths": { "thumbnail": "/app/uploads/2020/03/Screenshot-2022-03-14-at-11.51.27-150x87.png", "medium_large": "/app/uploads/2020/03/Screenshot-2022-03-14-at-11.51.27-768x443.png" } }

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The Spanish flu: The global impact of the largest influenza pandemic in history

spanish-flu-largest-influenza-pandemic-in-history

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<div class="blog-info">Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article — mostly the mortality estimates of the various influenza pandemics — were revised in May 2023.</div>   In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy, which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy <a href="https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time">has doubled</a> in all regions of the world.   What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the ‘Spanish flu’.   To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. Period life expectancy, which is the precise name for this measure, captures the mortality in one particular year. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year’s mortality pattern would remain constant throughout their entire lifetimes.   This influenza outbreak wasn’t restricted to Spain and it didn’t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. <a href="https://doi.org/10.1073/pnas.1324197111">https://doi.org/10.1073/pnas.1324197111 </a>Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. <a href="https://doi.org/10.1186/1479-5876-2-3">https://doi.org/10.1186/1479-5876-2-3</a> {/ref}    But it <a href="https://www.history.com/news/why-was-it-called-the-spanish-flu">was named</a> as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.   The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC <a href="https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html">here</a>.{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) – Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.   The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications:    McLane, J. R. (2013). <a href="https://sites.otago.ac.nz/Sites/article/view/215">Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies</a>, 10(2), 30-51.<a href="https://sites.otago.ac.nz/Sites/article/view/215"> </a>   Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}   <iframe src="https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA" style="width: 100%; height: 600px; border: 0px none;"></iframe>   <h4>How many people died in the Spanish flu pandemic?</h4>   <h5>The global death count of the flu today:</h5>   To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an “average of 389 000 (uncertainty range 294 000-518 000) respiratory deaths were associated with influenza globally each year”.   John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) – Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/">here</a>.{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)*100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today’s baseline.    <h5>Global deaths of the Spanish flu</h5>   Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu.    The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.   The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.   Johnson, N.P. and Mueller, J. (2002) – Updating the accounts: global mortality of the 1918-1920 “Spanish" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online <a href="https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents">here</a>.   The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}   Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths.   Patterson, K.D. and Pyle, G.F. (1991) – The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online <a href="https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf">here</a>.{/ref}   The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). "Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic". American Journal of Epidemiology. 187 (12): 2561–2567. doi:10.1093/aje/kwy191. PMID 30202996. Online <a href="https://academic.oup.com/aje/article/187/12/2561/5092383">here</a>.{/ref}   <h5>The global death rate of the Spanish flu</h5>   How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?   <a href="https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time">Estimates</a> suggest that the world population in 1918 was 1.8 billion.    Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)*100=0.95{/ref}   The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher – 100 million as these authors suggest – then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref}    The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like <a href="https://ourworldindata.org/grapher/population?country=OWID_WRL">this one</a>) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.   Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.   In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}   <h5>Other large influenza pandemics</h5>   The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic.    Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) – A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918–1919. BMC Infect Dis 19, 117 (2019). <a href="https://doi.org/10.1186/s12879-019-3750-8">https://doi.org/10.1186/s12879-019-3750-8</a>    According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.   Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}   Estimates for the death toll of the “Asian Flu” (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}   The same authors estimate that the “Hong Kong Flu” (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}   The “Russian Flu” pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. <a href="https://doi.org/10.1073/pnas.1324197111">https://doi.org/10.1073/pnas.1324197111</a> {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}   The “Swine flu” pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., … Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687–695. <a href="https://doi.org/10.1016/S1473-3099(12)70121-4">https://doi.org/10.1016/S1473-3099(12)70121-4</a>    Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. <a href="https://doi.org/10.1371/journal.pmed.1001558">https://doi.org/10.1371/journal.pmed.1001558</a>    Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. <a href="https://doi.org/10.1093/aje/kwy191">https://doi.org/10.1093/aje/kwy191</a> {/ref}   What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.   <figure class="wp-block-image size-full"><img src="https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png" alt="" class="wp-image-57012"/></figure>   <h4>The impact of the Spanish flu on different age groups</h4>   This last visualization here shows the life expectancy in England and Wales by age.    The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.   It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy ‘only’ increased because child mortality declined is <a href="https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age">not true</a>.   With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both <a href="https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017">lower respiratory infections (pneumonia)</a> and <a href="https://ourworldindata.org/grapher/death-rate-upper-respiratory-age">upper respiratory infections</a> today, death rates are highest for those who are 70 years and older.    This data tells us that young people <a href="https://ourworldindata.org/age-structure">accounted for a large share</a> of the deaths, this made this pandemic especially devastating.   Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak – the already discussed <a href="https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic">‘Russian flu pandemic’</a> of 1889–90 – which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) – Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/">here</a>.   The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.   Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}   The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online <a href="https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55">here</a>.{/ref}   <figure class="wp-block-image size-full"><img src="https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png" alt="" class="wp-image-30185"/></figure>   <h4>How the Spanish flu differs from the Coronavirus outbreak in 2020</h4>   Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.   They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.   The age-specific mortality seems to be very different. As we’ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) – The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online <a href="https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU">here</a>.{/ref}   We’ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.   But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time.    Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary bacterial infections. Morens et al (2008) found that during the Spanish flu “the majority of deaths … likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.”{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) – Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962–970. 10.1086/591708. Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/">here</a>.{/ref}   And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share <a href="https://ourworldindata.org/extreme-history-methods">was extremely poor</a> – large shares of the population were undernourished, in most parts of the world the populations lived <a href="https://ourworldindata.org/life-expectancy-globally">in very poor health</a>, and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent <a href="https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run">large shares</a> of their resources on the war.    While most of the world is <a href="https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts">much richer and healthier now</a>, the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Boëlle, Eric D’Ortenzio, et al. (2020) – “Preparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.” The Lancet (February 20, 2020).<a href="https://doi.org/10.1016/S0140-6736(20)30411-6"> https://doi.org/10.1016/S0140-6736(20)30411-6</a>.   See also   Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) – Effects of Response to 2014–2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433–441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667">here</a>.{/ref}   These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago.    But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response – WHO guidance document. Published in 2009 by the WHO. Online <a href="https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf">here</a>.Roman Duda (2016) – Problem profile: Biorisk reduction. Published by 80,000 hours. Online <a href="https://80000hours.org/problem-profiles/biosecurity/">here</a>.{/ref}

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                        "text": "Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article \u2014 mostly the mortality estimates of the various influenza pandemics \u2014 were revised in May 2023.",
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                        "text": "In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy,\u00a0which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy ",
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                        "url": "https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time",
                        "children": [
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                                "text": "has doubled",
                                "spanType": "span-simple-text"
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                        ],
                        "spanType": "span-link"
                    },
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                        "text": " in all regions of the world.",
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                        "text": "What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the \u2018Spanish flu\u2019.",
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                "value": [
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                        "text": "To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. ",
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                    {
                        "children": [
                            {
                                "text": "Period life expectancy",
                                "spanType": "span-simple-text"
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                    {
                        "text": ", which is the precise name for this measure, captures the mortality in ",
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                    {
                        "children": [
                            {
                                "text": "one particular year",
                                "spanType": "span-simple-text"
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                        ],
                        "spanType": "span-italic"
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                    {
                        "text": ". It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year\u2019s mortality pattern would remain constant throughout their entire lifetimes.",
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                        "text": "This influenza outbreak wasn\u2019t restricted to Spain and it didn\u2019t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1073/pnas.1324197111",
                        "children": [
                            {
                                "text": "https://doi.org/10.1073/pnas.1324197111",
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                            },
                            {
                                "spanType": "span-newline"
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                        ],
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                        "text": "Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1186/1479-5876-2-3",
                        "children": [
                            {
                                "text": "https://doi.org/10.1186/1479-5876-2-3",
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                            }
                        ],
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                    },
                    {
                        "text": " {/ref}\u00a0",
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                "type": "text",
                "value": [
                    {
                        "text": "But it ",
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                        "url": "https://www.history.com/news/why-was-it-called-the-spanish-flu",
                        "children": [
                            {
                                "text": "was named",
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                        "text": " as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.",
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                "value": [
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                        "text": "The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC ",
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                    },
                    {
                        "url": "https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html",
                        "children": [
                            {
                                "text": "here",
                                "spanType": "span-simple-text"
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                        "text": ".{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) \u2013 Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.",
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                "value": [
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                        "text": "The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications:\u00a0",
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                "value": [
                    {
                        "text": "McLane, J. R. (2013). ",
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                    },
                    {
                        "url": "https://sites.otago.ac.nz/Sites/article/view/215",
                        "children": [
                            {
                                "text": "Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies",
                                "spanType": "span-simple-text"
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                        ],
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                    },
                    {
                        "text": ", 10(2), 30-51.",
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                        "url": "https://sites.otago.ac.nz/Sites/article/view/215",
                        "children": [
                            {
                                "text": "\u00a0",
                                "spanType": "span-simple-text"
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                        "text": "Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}",
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                ],
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                "url": "https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA",
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                "text": [
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                        "text": "How many people died in the Spanish flu pandemic?",
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                "text": [
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                        "text": "The global death count of the flu today:",
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                        "text": "To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an \u201caverage of 389\u2009000 (uncertainty range 294\u2009000-518\u2009000) respiratory deaths were associated with influenza globally each year\u201d.",
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                "value": [
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                        "text": "John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) \u2013 Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online ",
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                        "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/",
                        "children": [
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                                "text": "here",
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                        "text": ".{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)*100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today\u2019s baseline.\u00a0",
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                "text": [
                    {
                        "text": "Global deaths of the Spanish flu",
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                "value": [
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                        "text": "Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu.\u00a0",
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                        "text": "The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.",
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                        "text": "The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: ",
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                        "children": [
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                                "text": "Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.",
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                        "text": "Johnson, N.P. and Mueller, J. (2002) \u2013 Updating the accounts: global mortality of the 1918-1920 \u201cSpanish\" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online ",
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                    },
                    {
                        "url": "https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents",
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                                "text": "here",
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                        "text": ".",
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                "value": [
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                        "text": "The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}",
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                "value": [
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                        "text": "Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths.",
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                "value": [
                    {
                        "text": "Patterson, K.D. and Pyle, G.F. (1991) \u2013 The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf",
                        "children": [
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                                "text": "here",
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                        "text": ".{/ref}",
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                "value": [
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                        "text": "The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). \"Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic\". American Journal of Epidemiology. 187 (12): 2561\u20132567. doi:10.1093/aje/kwy191. PMID 30202996. Online ",
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                        "text": ".{/ref}",
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                "text": [
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                        "text": "The global death rate of the Spanish flu",
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                "value": [
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                        "text": "How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?",
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                        "url": "https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time",
                        "children": [
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                                "text": "Estimates",
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                        "text": " suggest that the world population in 1918 was 1.8 billion.\u00a0",
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                        "text": "Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)*100=0.95{/ref}",
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                        "text": "The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher\u00a0\u2013 100 million as these authors suggest \u2013 then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref}\u00a0",
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                "value": [
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                        "text": "The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like ",
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                    {
                        "url": "https://ourworldindata.org/grapher/population?country=OWID_WRL",
                        "children": [
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                                "text": "this one",
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                        "text": ") this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.",
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                "value": [
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                        "text": "Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.",
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                        "text": "In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}",
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                "text": [
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                        "text": "Other large influenza pandemics",
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                "value": [
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                        "text": "The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic.\u00a0",
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                "value": [
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                        "text": "Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) \u2013 A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918\u20131919. BMC Infect Dis 19, 117 (2019). ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1186/s12879-019-3750-8",
                        "children": [
                            {
                                "text": "https://doi.org/10.1186/s12879-019-3750-8",
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                "value": [
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                        "text": "According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.",
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                "type": "text",
                "value": [
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                        "text": "Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ",
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                    {
                        "url": "https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55",
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                                "text": "here",
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                        "text": ".{/ref}",
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                "value": [
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                        "text": "Estimates for the death toll of the \u201cAsian Flu\u201d (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ",
                        "spanType": "span-simple-text"
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                    {
                        "url": "https://doi.org/10.1093/aje/kwy191",
                        "children": [
                            {
                                "text": "https://doi.org/10.1093/aje/kwy191",
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                        "text": " {/ref}",
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                "type": "text",
                "value": [
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                        "text": "The same authors estimate that the \u201cHong Kong Flu\u201d (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1093/aje/kwy191",
                        "children": [
                            {
                                "text": "https://doi.org/10.1093/aje/kwy191",
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                        "text": " {/ref}",
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                "value": [
                    {
                        "text": "The \u201cRussian Flu\u201d pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1073/pnas.1324197111",
                        "children": [
                            {
                                "text": "https://doi.org/10.1073/pnas.1324197111",
                                "spanType": "span-simple-text"
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                        ],
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                    },
                    {
                        "text": " {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1093/aje/kwy191",
                        "children": [
                            {
                                "text": "https://doi.org/10.1093/aje/kwy191",
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                        "text": " {/ref}",
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                "type": "text",
                "value": [
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                        "text": "The \u201cSwine flu\u201d pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., \u2026 Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687\u2013695. ",
                        "spanType": "span-simple-text"
                    },
                    {
                        "url": "https://doi.org/10.1016/S1473-3099(12)70121-4",
                        "children": [
                            {
                                "text": "https://doi.org/10.1016/S1473-3099(12)70121-4",
                                "spanType": "span-simple-text"
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                        "text": "Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. ",
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                    },
                    {
                        "url": "https://doi.org/10.1371/journal.pmed.1001558",
                        "children": [
                            {
                                "text": "https://doi.org/10.1371/journal.pmed.1001558",
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                        "text": "Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. ",
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                    {
                        "url": "https://doi.org/10.1093/aje/kwy191",
                        "children": [
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                                "text": "https://doi.org/10.1093/aje/kwy191",
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                        "text": " {/ref}",
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                        "text": "What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.",
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                "text": [
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                        "text": "The impact of the Spanish flu on different age groups",
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                        "text": "This last visualization here shows the life expectancy in England and Wales by age.\u00a0",
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                "value": [
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                        "text": "The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.",
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                "value": [
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                        "text": "It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy \u2018only\u2019 increased because child mortality declined is ",
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                        "url": "https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age",
                        "children": [
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                                "text": "not true",
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                        "text": ".",
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                        "text": "With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both ",
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                    {
                        "url": "https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017",
                        "children": [
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                                "text": "lower respiratory infections (pneumonia)",
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                    {
                        "text": " and ",
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                                "text": "upper respiratory infections",
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                        "text": " today, death rates are highest for those who are 70 years and older.\u00a0",
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                "value": [
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                        "text": "This data tells us that young people ",
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                        "children": [
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                                "text": "accounted for a large share",
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                        "text": " of the deaths, this made this pandemic especially devastating.",
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                        "text": "Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak \u2013 the already discussed ",
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                    {
                        "url": "https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic",
                        "children": [
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                                "text": "\u2018Russian flu pandemic\u2019",
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                        "text": " of 1889\u201390 \u2013 which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) \u2013 Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online ",
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                        "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/",
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                                "text": "here",
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                        "text": "The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.",
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                "value": [
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                        "text": "Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ",
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                        "text": "The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online ",
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                "text": [
                    {
                        "text": "How the Spanish flu differs from the Coronavirus outbreak in 2020",
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                        "text": "Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.",
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                        "text": "They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.",
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                        "text": "The age-specific mortality seems to be very different. As we\u2019ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) \u2013 The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online ",
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                        "url": "https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU",
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                        "text": ".{/ref}",
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                        "text": "We\u2019ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.",
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                        "text": "But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time.\u00a0",
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                        "text": "Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary ",
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                        "children": [
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                                "text": "bacterial",
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                        "text": " infections. Morens et al (2008) found that during the Spanish flu \u201cthe majority of deaths \u2026 likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory\u2013tract bacteria.\u201d{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) \u2013 Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962\u2013970. 10.1086/591708. Online ",
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                        "text": "And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share ",
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                        "text": ", and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent ",
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                        "text": " of their resources on the war.\u00a0",
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                        "text": ", the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Bo\u00eblle, Eric D\u2019Ortenzio, et al. (2020) \u2013 \u201cPreparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.\u201d ",
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                        "text": " (February 20, 2020).",
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                        "text": "Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) \u2013 Effects of Response to 2014\u20132015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433\u2013441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online ",
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                        "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667",
                        "children": [
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                                "text": "here",
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                        "text": ".{/ref}",
                        "spanType": "span-simple-text"
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                        "text": "These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago.\u00a0",
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                        "text": "But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response \u2013 WHO guidance document. Published in 2009 by the WHO. Online ",
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                        "url": "https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf",
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                                "text": "here",
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                        "text": ".Roman Duda (2016) \u2013 Problem profile: Biorisk reduction. Published by 80,000 hours. Online ",
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                        "url": "https://80000hours.org/problem-profiles/biosecurity/",
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                                "text": "here",
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2020-03-04 10:23:59

2024-02-16 14:22:49

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2020-03-04 10:23:17

2023-05-17 21:16:43

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Our World in Data presents the data and research to make progress against the world's largest problems. Parts of the article — mostly the mortality estimates of the various influenza pandemics — were revised in May 2023. In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy, which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy [has doubled](https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time) in all regions of the world. What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the ‘Spanish flu’. To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. _Period life expectancy_, which is the precise name for this measure, captures the mortality in _one particular year_. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year’s mortality pattern would remain constant throughout their entire lifetimes. This influenza outbreak wasn’t restricted to Spain and it didn’t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. [https://doi.org/10.1073/pnas.1324197111 ](https://doi.org/10.1073/pnas.1324197111)Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. [https://doi.org/10.1186/1479-5876-2-3](https://doi.org/10.1186/1479-5876-2-3) {/ref} But it [was named](https://www.history.com/news/why-was-it-called-the-spanish-flu) as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time. The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC [here](https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html).{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) – Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books. The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications: McLane, J. R. (2013). [Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies](https://sites.otago.ac.nz/Sites/article/view/215), 10(2), 30-51.[ ](https://sites.otago.ac.nz/Sites/article/view/215) Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref} <Chart url="https://ourworldindata.org/grapher/life-expectancy?tab=chart&country=FIN~NOR~ESP~SWE~CHE~USA"/> ## How many people died in the Spanish flu pandemic? ### The global death count of the flu today: To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an “average of 389 000 (uncertainty range 294 000-518 000) respiratory deaths were associated with influenza globally each year”. John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) – Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/).{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)*100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today’s baseline. ### Global deaths of the Spanish flu Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu. The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide. The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: _Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated._ Johnson, N.P. and Mueller, J. (2002) – Updating the accounts: global mortality of the 1918-1920 “Spanish" influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online [here](https://www.jstor.org/stable/44446153?read-now=1&seq=1#page_scan_tab_contents). The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref} Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote 'we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918' and published a range from 24.7-39.3 million deaths. Patterson, K.D. and Pyle, G.F. (1991) – The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online [here](https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf).{/ref} The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). "Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic". American Journal of Epidemiology. 187 (12): 2561–2567. doi:10.1093/aje/kwy191. PMID 30202996. Online [here](https://academic.oup.com/aje/article/187/12/2561/5092383).{/ref} ### The global death rate of the Spanish flu How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic? [Estimates](https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time) suggest that the world population in 1918 was 1.8 billion. Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)*100=0.95{/ref} The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher – 100 million as these authors suggest – then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref} The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like [this one](https://ourworldindata.org/grapher/population?country=OWID_WRL)) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past. Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates. In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref} ### Other large influenza pandemics The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic. Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) – A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918–1919. BMC Infect Dis 19, 117 (2019). [https://doi.org/10.1186/s12879-019-3750-8](https://doi.org/10.1186/s12879-019-3750-8) According to Smith (1995) 132,000 died in England, Wales, and Ireland alone. Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} Estimates for the death toll of the “Asian Flu” (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The same authors estimate that the “Hong Kong Flu” (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The “Russian Flu” pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., & Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107–8112. [https://doi.org/10.1073/pnas.1324197111](https://doi.org/10.1073/pnas.1324197111) {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} The “Swine flu” pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., … Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687–695. [https://doi.org/10.1016/S1473-3099(12)70121-4](https://doi.org/10.1016/S1473-3099(12)70121-4) Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., & the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. [https://doi.org/10.1371/journal.pmed.1001558](https://doi.org/10.1371/journal.pmed.1001558) Spreeuwenberg, P., Kroneman, M., & Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561–2567. [https://doi.org/10.1093/aje/kwy191](https://doi.org/10.1093/aje/kwy191) {/ref} What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history. <Image filename="Influenza-pandemics-in-comparison-1.png" alt=""/> ## The impact of the Spanish flu on different age groups This last visualization here shows the life expectancy in England and Wales by age. The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10. It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy ‘only’ increased because child mortality declined is [not true](https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age). With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both [lower respiratory infections (pneumonia)](https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017) and [upper respiratory infections](https://ourworldindata.org/grapher/death-rate-upper-respiratory-age) today, death rates are highest for those who are 70 years and older. This data tells us that young people [accounted for a large share](https://ourworldindata.org/age-structure) of the deaths, this made this pandemic especially devastating. Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak – the already discussed [‘Russian flu pandemic’](https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic) of 1889–90 – which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) – Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/). The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland. Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) – The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55–73. Online [here](https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55).{/ref} <Image filename="Life-expectancy-by-age-in-the-UK-1700-to-2013.png" alt=""/> ## How the Spanish flu differs from the Coronavirus outbreak in 2020 Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered. They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above. The age-specific mortality seems to be very different. As we’ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) – The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online [here](https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU).{/ref} We’ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past. But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time. Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary _bacterial_ infections. Morens et al (2008) found that during the Spanish flu “the majority of deaths … likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.”{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) – Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962–970. 10.1086/591708. Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/).{/ref} And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share [was extremely poor](https://ourworldindata.org/extreme-history-methods) – large shares of the population were undernourished, in most parts of the world the populations lived [in very poor health](https://ourworldindata.org/life-expectancy-globally), and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent [large shares](https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run) of their resources on the war. While most of the world is [much richer and healthier now](https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts), the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Boëlle, Eric D’Ortenzio, et al. (2020) – “Preparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.” _The Lancet_ (February 20, 2020).[ https://doi.org/10.1016/S0140-6736(20)30411-6](https://doi.org/10.1016/S0140-6736(20)30411-6). See also Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) – Effects of Response to 2014–2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433–441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online [here](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667).{/ref} These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago. But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response – WHO guidance document. Published in 2009 by the WHO. Online [here](https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf).Roman Duda (2016) – Problem profile: Biorisk reduction. Published by 80,000 hours. Online [here](https://80000hours.org/problem-profiles/biosecurity/).{/ref}

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        "rendered": "\n<div class=\"blog-info\">Our World in Data presents the data and research to make progress against the world&#8217;s largest problems. Parts of the article \u2014 mostly the mortality estimates of the various influenza pandemics \u2014 were revised in May 2023.</div>\n\n\n\n<p>In the last 150 years the world has seen an unprecedented improvement in health. The visualization shows that in many countries life expectancy,&nbsp;which measures the average age of death, doubled from around 40 years or less to more than 80 years. This was not just an achievement across the countries shown here; life expectancy <a href=\"https://ourworldindata.org/life-expectancy#how-did-life-expectancy-change-over-time\">has doubled</a> in all regions of the world.</p>\n\n\n\n<p>What also stands out is how abrupt and damning negative health events can be. Most striking is the large, sudden decline of life expectancy in 1918, caused by an unusually deadly influenza pandemic that became known as the \u2018Spanish flu\u2019.</p>\n\n\n\n<p>To make sense of the fact life expectancy declined so abruptly, one has to keep in mind what it measures. <em>Period life expectancy</em>, which is the precise name for this measure, captures the mortality in <em>one particular year</em>. It summarizes the mortality in a particular year by calculating the average age of death of a hypothetical cohort of people for which that year\u2019s mortality pattern would remain constant throughout their entire lifetimes.</p>\n\n\n\n<p>This influenza outbreak wasn\u2019t restricted to Spain and it didn\u2019t even originate there. Recent genetic research suggests that the strain emerged a few years earlier, around 1915, but did not take off until later on. The earliest recorded outbreak was in Kansas in the United States in 1918.{ref}Worobey, M., Han, G.-Z., &amp; Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. <a href=\"https://doi.org/10.1073/pnas.1324197111\">https://doi.org/10.1073/pnas.1324197111<br></a>Barry, J. M. (2004). The site of origin of the 1918 influenza pandemic and its public health implications. Journal of Translational Medicine, 2(1), 3. <a href=\"https://doi.org/10.1186/1479-5876-2-3\">https://doi.org/10.1186/1479-5876-2-3</a> {/ref}&nbsp;</p>\n\n\n\n<p>But it <a href=\"https://www.history.com/news/why-was-it-called-the-spanish-flu\">was named</a> as such because Spain was neutral in the First World War (1914-18), which meant it was free to report on the severity of the pandemic, while countries that were fighting tried to suppress reports on how the influenza impacted their population to maintain morale and not appear weakened in the eyes of the enemies. Since it is very valuable to speak openly about the threat of an infectious disease I think Spain should be proud that it was not like other countries at that time.</p>\n\n\n\n<p>The virus spread rapidly and eventually reached all parts of the world: the epidemic became a pandemic.{ref}For the definitions of epidemic and pandemic see the CDC <a href=\"https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html\">here</a>.{/ref} Even in a much less-connected world the virus eventually reached extremely remote places such as the Alaskan wilderness and Samoa in the middle of the Pacific islands. In these remote places the mortality rate was often particularly high.{ref}Burnet F. M., Clark E. (1942) \u2013 Influenza: A Survey of the Last 50 Years in the Light of Modern Work on the Virus of Epidemic Influenza. London: Macmillan. Partly online on Google books.</p>\n\n\n\n<p>The mortality rate in some populations like Alaska and Samoa were said to be 90% and 25% respectively. See the following two publications:&nbsp;</p>\n\n\n\n<p>McLane, J. R. (2013). <a href=\"https://sites.otago.ac.nz/Sites/article/view/215\">Paradise locked: The 1918 influenza pandemic in American Samoa. Sites: a journal of social anthropology and cultural studies</a>, 10(2), 30-51.<a href=\"https://sites.otago.ac.nz/Sites/article/view/215\">&nbsp;</a></p>\n\n\n\n<p>Mamelund, S. E. (2017). Profiling a Pandemic. Who were the victims of the Spanish flu?{ref} While peak mortality was reached in 1918 the pandemic did not wane until two years later in late 1920.{/ref}</p>\n\n\n\n<iframe src=\"https://ourworldindata.org/grapher/life-expectancy?tab=chart&amp;country=FIN~NOR~ESP~SWE~CHE~USA\" style=\"width: 100%; height: 600px; border: 0px none;\"></iframe>\n\n\n\n<h4>How many people died in the Spanish flu pandemic?</h4>\n\n\n\n<h5>The global death count of the flu today:</h5>\n\n\n\n<p>To have a context for the severity of influenza pandemics it might be helpful to know the death count of a typical flu season. Current estimates for the annual number of deaths from influenza are around 400,000 deaths per year. Paget et al (2019) suggest an average of 389,000 with an uncertainty range 294,000 from 518,000.{ref}Paget et al (2019) suggest an \u201caverage of 389\u2009000 (uncertainty range 294\u2009000-518\u2009000) respiratory deaths were associated with influenza globally each year\u201d.</p>\n\n\n\n<p>John Paget, Peter Spreeuwenberg, Vivek Charu Robert J Taylor, A Danielle Iuliano, Joseph Bresee, Lone Simonsen, Cecile Viboud,3 and for the Global Seasonal Influenza-associated Mortality Collaborator Network and GLaMOR Collaborating Teams (2019) \u2013 Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project. In J Glob Health. 2019 Dec; 9(2): 020421. Published online 2019 Oct 22. doi: 10.7189/jogh.09.020421 PMCID: PMC6815659 PMID: 31673337 Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/\">here</a>.{/ref} This means that in recent years the flu was responsible for the death of 0.005% of the world population.{ref}(389,000/7,500,000,000)*100=0.0052%{/ref} Even in comparison to the low estimate for the death count of the Spanish flu (17.4 million) this pandemic, more than a century ago, caused a death rate that was 182-times higher than today\u2019s baseline.&nbsp;</p>\n\n\n\n<h5>Global deaths of the Spanish flu</h5>\n\n\n\n<p>Several research teams have worked on the difficult problem of reconstructing the global health impact of the Spanish flu.&nbsp;</p>\n\n\n\n<p>The visualization here shows the available estimates from the different research publications discussed in the following. The range of published estimates for the Spanish flu is particularly wide.</p>\n\n\n\n<p>The widely cited study by Johnson and Mueller (2002) arrives at a very high estimate of at least 50 million global deaths. But the authors suggest that this could be an underestimation and that the true death toll was as high as 100 million.{ref}From the paper: <em>Further research has seen the consistent upward revision of the estimated global mortality of the pandemic, which a 1920s calculation put in the vicinity of 21.5 million. A 1991 paper revised the mortality as being in the range 24.7-39.3 million. This paper suggests that it was of the order of 50 million. However, it must be acknowledged that even this vast figure may be substantially lower than the real toll, perhaps as much as 100 percent understated.</em></p>\n\n\n\n<p>Johnson, N.P. and Mueller, J. (2002) \u2013 Updating the accounts: global mortality of the 1918-1920 \u201cSpanish&#8221; influenza pandemic. In Bulletin of the History of Medicine, 76(1), pp.105-115. Online <a href=\"https://www.jstor.org/stable/44446153?read-now=1&amp;seq=1#page_scan_tab_contents\">here</a>.</p>\n\n\n\n<p>The paper includes detailed breakdowns of mortality estimates by world region and country.{/ref}</p>\n\n\n\n<p>Patterson and Pyle (1991) estimated that between 24.7 and 39.3 million died from the pandemic.{ref}Patterson and Pyle (1991) wrote &#8216;we believe that approximately 30 million is the best estimate for the terrible demographic toll of the influenza pandemic of 1918&#8217; and published a range from 24.7-39.3 million deaths.</p>\n\n\n\n<p>Patterson, K.D. and Pyle, G.F. (1991) \u2013 The geography and mortality of the 1918 influenza pandemic. Bulletin of the History of Medicine, 65(1), p.4. Online <a href=\"https://web.archive.org/web/20171022101640/https://pida.nihlibrary.com/sites/pida.nihlibrary.com/files/pdf_files/1991_K.David%20Patterson_The%20geography%20and%20mortality%20of%20the%201918%20influenza%20pandemic..pdf\">here</a>.{/ref}</p>\n\n\n\n<p>The more recent study by Spreeuwenberg et al. (2018) concluded that earlier estimates have been too high. Their own estimate is 17.4 million deaths.{ref}P. Spreeuwenberg; et al. (1 December 2018). &#8220;Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic&#8221;. American Journal of Epidemiology. 187 (12): 2561\u20132567. doi:10.1093/aje/kwy191. PMID 30202996. Online <a href=\"https://academic.oup.com/aje/article/187/12/2561/5092383\">here</a>.{/ref}</p>\n\n\n\n<h5>The global death rate of the Spanish flu</h5>\n\n\n\n<p>How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?</p>\n\n\n\n<p><a href=\"https://ourworldindata.org/world-population-growth#how-has-world-population-growth-changed-over-time\">Estimates</a> suggest that the world population in 1918 was 1.8 billion.&nbsp;</p>\n\n\n\n<p>Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% of the world population.{ref}The calculation is (17,400,000/1,832,196,157)*100=0.95{/ref}</p>\n\n\n\n<p>The estimate of 50 million deaths published by Johnson and Mueller implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher&nbsp;\u2013 100 million as these authors suggest \u2013 then the global death rate would have been 5.4%.{ref}50,000,000 deaths / 1,832,196,157 people = 0.02729 And with a death count twice is high: 0.05458.{/ref}&nbsp;</p>\n\n\n\n<p>The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.{ref}In available historical reconstructions (like <a href=\"https://ourworldindata.org/grapher/population?country=OWID_WRL\">this one</a>) this decline is not shown. The reason for this is that precise annual counts of the world population are not available for the past.</p>\n\n\n\n<p>Instead historians try to reconstruct the population figures for 5-year or 10-year intervals and the annual estimates are interpolations between these estimates.</p>\n\n\n\n<p>In other words, if we had precise annual counts they would likely show a decline of the world population in 1918.{/ref}</p>\n\n\n\n<h5>Other large influenza pandemics</h5>\n\n\n\n<p>The Spanish flu pandemic was the largest, but not the only large recent influenza pandemic.&nbsp;</p>\n\n\n\n<p>Two decades before the Spanish flu the Russian flu pandemic (1889-1894) is believed to have killed 1 million people.{ref}Nickol, M.E., Kindrachuk, J. (2019) \u2013 A year of terror and a century of reflection: perspectives on the great influenza pandemic of 1918\u20131919. BMC Infect Dis 19, 117 (2019). <a href=\"https://doi.org/10.1186/s12879-019-3750-8\">https://doi.org/10.1186/s12879-019-3750-8</a>&nbsp;</p>\n\n\n\n<p>According to Smith (1995) 132,000 died in England, Wales, and Ireland alone.</p>\n\n\n\n<p>Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<p>Estimates for the death toll of the \u201cAsian Flu\u201d (1957-1958) range from 1.7 to 2.7 million according to Spreeuwenberg et al. (2018).{ref}Spreeuwenberg, P., Kroneman, M., &amp; Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The same authors estimate that the \u201cHong Kong Flu\u201d (1968-1969) killed between 2 and 3.8 million people.{ref}Spreeuwenberg, P., Kroneman, M., &amp; Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The \u201cRussian Flu\u201d pandemic of 1889-1890 is believed to be caused by an H3 pandemic virus.{ref}Worobey, M., Han, G.-Z., &amp; Rambaut, A. (2014). Genesis and pathogenesis of the 1918 pandemic H1N1 influenza A virus. Proceedings of the National Academy of Sciences, 111(22), 8107\u20138112. <a href=\"https://doi.org/10.1073/pnas.1324197111\">https://doi.org/10.1073/pnas.1324197111</a> {/ref} According to Spreeuwenberg et al. (2018) around 3.7 to 5.1 million people died worldwide.{ref}Spreeuwenberg, P., Kroneman, M., &amp; Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>The \u201cSwine flu\u201d pandemic of 2009-2010 was caused by a new H1N1 pandemic virus. Several research groups have made estimates of the global death toll, which ranges from 130,000 to 1.87 million people worldwide.{ref}Dawood, F. S., Iuliano, A. D., Reed, C., Meltzer, M. I., Shay, D. K., Cheng, P.-Y., Bandaranayake, D., Breiman, R. F., Brooks, W. A., Buchy, P., Feikin, D. R., Fowler, K. B., Gordon, A., Hien, N. T., Horby, P., Huang, Q. S., Katz, M. A., Krishnan, A., Lal, R., \u2026 Widdowson, M.-A. (2012). Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: A modelling study. The Lancet Infectious Diseases, 12(9), 687\u2013695. <a href=\"https://doi.org/10.1016/S1473-3099(12)70121-4\">https://doi.org/10.1016/S1473-3099(12)70121-4</a>&nbsp;</p>\n\n\n\n<p>Simonsen, L., Spreeuwenberg, P., Lustig, R., Taylor, R. J., Fleming, D. M., Kroneman, M., Van Kerkhove, M. D., Mounts, A. W., Paget, W. J., &amp; the GLaMOR Collaborating Teams. (2013). Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. PLoS Medicine, 10(11), e1001558. <a href=\"https://doi.org/10.1371/journal.pmed.1001558\">https://doi.org/10.1371/journal.pmed.1001558</a>&nbsp;</p>\n\n\n\n<p>Spreeuwenberg, P., Kroneman, M., &amp; Paget, J. (2018). Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic. American Journal of Epidemiology, 187(12), 2561\u20132567. <a href=\"https://doi.org/10.1093/aje/kwy191\">https://doi.org/10.1093/aje/kwy191</a> {/ref}</p>\n\n\n\n<p>What becomes clear from this overview are two things: influenza pandemics are not rare, but the Spanish flu of 1918 was by far the most devastating influenza pandemic in recorded history.</p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" width=\"2410\" height=\"1767\" src=\"https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png\" alt=\"\" class=\"wp-image-57012\" srcset=\"https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1.png 2410w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-400x293.png 400w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-750x550.png 750w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-150x110.png 150w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-768x563.png 768w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-1536x1126.png 1536w, https://owid.cloud/app/uploads/2023/05/Influenza-pandemics-in-comparison-1-2048x1502.png 2048w\" sizes=\"(max-width: 2410px) 100vw, 2410px\" /></figure>\n\n\n\n<h4>The impact of the Spanish flu on different age groups</h4>\n\n\n\n<p>This last visualization here shows the life expectancy in England and Wales by age.&nbsp;</p>\n\n\n\n<p>The red line shows the life expectancy for a newborn, with the rainbow-colored lines above showing how long a person could expect to live once they had reached that given, older, age. The light green line, for example, represents the life expectancy for children who have reached age 10.</p>\n\n\n\n<p>It shows that life expectancy increased at all ages, which means that the often-heard assertion that life expectancy \u2018only\u2019 increased because child mortality declined is <a href=\"https://ourworldindata.org/life-expectancy#it-is-not-only-about-child-mortality-life-expectancy-by-age\">not true</a>.</p>\n\n\n\n<p>With respect to the impact of the Spanish flu it is striking that the visualization shows that the pandemic had little impact on older people. While the life expectancy at birth and at young ages declined by more than ten years, the life expectancy of 60- and 70-year olds saw no change. This is at odds with what one would reasonably expect: older populations tend to be most vulnerable to influenza outbreaks and respiratory infections. If we look at mortality for both <a href=\"https://ourworldindata.org/grapher/pneumonia-mortality-by-age?time=2017\">lower respiratory infections (pneumonia)</a> and <a href=\"https://ourworldindata.org/grapher/death-rate-upper-respiratory-age\">upper respiratory infections</a> today, death rates are highest for those who are 70 years and older.&nbsp;</p>\n\n\n\n<p>This data tells us that young people <a href=\"https://ourworldindata.org/age-structure\">accounted for a large share</a> of the deaths, this made this pandemic especially devastating.</p>\n\n\n\n<p>Why were older people so resilient to the 1918 pandemic? The research literature suggests that this was the case because older people had lived through an earlier flu outbreak \u2013 the already discussed <a href=\"https://en.wikipedia.org/wiki/1889%E2%80%9390_flu_pandemic\">\u2018Russian flu pandemic\u2019</a> of 1889\u201390 \u2013 which gave those who lived through it some immunity for the later outbreak of the Spanish flu.{ref}Gagnon et al. (2013) \u2013 Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.PLoS One. 2013; 8(8): e69586. Published online 2013 Aug 5. doi: 10.1371/journal.pone.0069586. Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734171/\">here</a>.</p>\n\n\n\n<p>The Russian flu pandemic was a devastating event in itself. Smith (1995) estimates that the Russian flu killed 132,000 in England, Wales, and Ireland.</p>\n\n\n\n<p>Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<p>The earlier 1889-90 pandemic might have given the older population some immunity, but was a destructive event in itself. According to Smith 132,000 people died in England, Wales, and Ireland alone.{ref}Smith F. B. (1995) \u2013 The Russian influenza in the United Kingdom, 1889-1894. Soc. Hist. Med. 8 55\u201373. Online <a href=\"https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/8.1.55\">here</a>.{/ref}</p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" width=\"3080\" height=\"2050\" src=\"https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png\" alt=\"\" class=\"wp-image-30185\" srcset=\"https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013.png 3080w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-400x266.png 400w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-800x532.png 800w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-150x100.png 150w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-768x511.png 768w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-1536x1022.png 1536w, https://owid.cloud/app/uploads/2020/03/Life-expectancy-by-age-in-the-UK-1700-to-2013-2048x1363.png 2048w\" sizes=\"(max-width: 3080px) 100vw, 3080px\" /></figure>\n\n\n\n<h4>How the Spanish flu differs from the Coronavirus outbreak in 2020</h4>\n\n\n\n<p>Writing in early March 2020 it is an obvious question to ask how the ongoing outbreak of Covid-19 compares. There are a number of important differences that should be considered.</p>\n\n\n\n<p>They are not the same disease and the virus causing these diseases are very different. The virus that causes Covid-19 is a coronavirus, not an influenza virus that caused the Spanish flu and the other influenza pandemics listed above.</p>\n\n\n\n<p>The age-specific mortality seems to be very different. As we\u2019ve seen above, the Spanish flu in 1918 was especially dangerous to infants and younger people. The new coronavirus that causes Covid-19 appears to be most lethal to the elderly, based on early evidence in China.{ref}Zhonghua Liu Xing Bing Xue Za Zhi (2020) \u2013 The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003. Online <a href=\"https://www.ncbi.nlm.nih.gov/pubmed/32064853?fbclid=IwAR3JCxH50VTfg3Q_02YTLdz2Tk7yBTmt-5oCxE4KlBe0evh7ByK3HPVU-pU\">here</a>.{/ref}</p>\n\n\n\n<p>We\u2019ve also seen above that during the Spanish flu many countries tried to suppress any information about the influenza outbreak. Today the sharing of data, research, and news is certainly not perfect, but very different and much more open than in the past.</p>\n\n\n\n<p>But it is true that the world today is much better connected. In 1918 it was railroads and steamships that connected the world. Today planes can carry people and viruses to many corners of the world in a very short time.&nbsp;</p>\n\n\n\n<p>Differences in health systems and infrastructure also matter. The Spanish flu hit the world in the days before antibiotics were invented; and many deaths, perhaps most, were not caused by the influenza virus itself, but by secondary <em>bacterial</em> infections. Morens et al (2008) found that during the Spanish flu \u201cthe majority of deaths \u2026 likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory\u2013tract bacteria.\u201d{ref}Morens D. M., Taubenberger J. K., Fauci A. S. (2008) \u2013 Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness. J. Infect. Dis. 198 962\u2013970. 10.1086/591708. Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599911/\">here</a>.{/ref}</p>\n\n\n\n<p>And not just health systems were different, but also the health and living conditions of the global population. The 1918 flu hit a world population of which a very large share <a href=\"https://ourworldindata.org/extreme-history-methods\">was extremely poor</a> \u2013 large shares of the population were undernourished, in most parts of the world the populations lived <a href=\"https://ourworldindata.org/life-expectancy-globally\">in very poor health</a>, and overcrowding, poor sanitation and low hygiene standards were common. Additionally the populations in many parts of the world were weakened by a global war. Public resources were small and many countries had just spent <a href=\"https://ourworldindata.org/military-spending#defence-spending-in-uk-over-the-very-long-run\">large shares</a> of their resources on the war.&nbsp;</p>\n\n\n\n<p>While most of the world is <a href=\"https://ourworldindata.org/a-history-of-global-living-conditions-in-5-charts\">much richer and healthier now</a>, the concern today too is that it is the poorest people that are going to be hit hardest by the Covid-19 outbreak.{ref}Gilbert, Marius, Giulia Pullano, Francesco Pinotti, Eugenio Valdano, Chiara Poletto, Pierre-Yves Bo\u00eblle, Eric D\u2019Ortenzio, et al. (2020) \u2013 \u201cPreparedness and Vulnerability of African Countries against Importations of COVID-19: A Modelling Study.\u201d <em>The Lancet</em> (February 20, 2020).<a href=\"https://doi.org/10.1016/S0140-6736(20)30411-6\"> https://doi.org/10.1016/S0140-6736(20)30411-6</a>.</p>\n\n\n\n<p>See also</p>\n\n\n\n<p>Alyssa S. Parpia, Martial L. Ndeffo-Mbah, Natasha S. Wenzel, and Alison P. Galvani (2016) \u2013 Effects of Response to 2014\u20132015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa. In Emerg Infect Dis. 2016 Mar; 22(3): 433\u2013441. doi: 10.3201/eid2203.150977 PMCID: PMC4766886 PMID: 26886846 Online <a href=\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766886/?fbclid=IwAR26EF-QA82ds5Jz81NNrIHb77S3n8L9D5YnL3GlLSRmQ3ms051ZCVx0zt8#!po=16.6667\">here</a>.{/ref}</p>\n\n\n\n<p>These differences suggest that one should be cautious in drawing lessons from the outbreak a century ago.&nbsp;</p>\n\n\n\n<p>But the Spanish flu reminds us just how large the impact of a pandemic can be, even in countries that had already been successful in improving population health. A new pathogen can cause terrible devastation and lead to the death of millions. For this reason the Spanish flu has been cited as a warning and as a motivation to prepare well for large pandemic outbreaks, which have been considered likely by many researchers.{ref}See for example: Pandemic influenza preparedness and response \u2013 WHO guidance document. Published in 2009 by the WHO. Online <a href=\"https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf\">here</a>.Roman Duda (2016) \u2013 Problem profile: Biorisk reduction. Published by 80,000 hours. Online <a href=\"https://80000hours.org/problem-profiles/biosecurity/\">here</a>.{/ref}</p>\n",
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