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  • Writer's pictureWilliam Miller, MD

The 1918 Influenza Pandemic – Part 3

Updated: Jul 14, 2021

This is our final part in the series looking at the 1918 Influenza Pandemic. It started in early 1918 and lasted about two years, officially ending in April 1920. During those two years, it went around the world in four big waves, with the second wave being the largest and most deadly. Fully 500 million people or one-third of the world population was infected. There were only 1.5 billion humans on the planet 100 years ago compared with the approximately 8 billion today. While COVID has infected approximately 160 million people at this time, that is only 2% of the world’s population compared to 30%.


During the two years of the 1918 pandemic, the virus mutated several times. There appears to have been at least three different strains that accounted for most of the cases.

At least 30 million people died. However, due to the lack of a global health organization tracking such things the actual number of deaths is thought to be much higher with most estimates starting at 50 million and some topping off at 100 million. Because the second wave, which was also in 1918 was the deadliest, most of those deaths were in the first year of the pandemic. Even with COVID’s 3.3 million worldwide deaths at the one-year mark, the 1918 Influenza Pandemic wins hands-down as the deadliest pandemic in recorded history.

In 1918, the US had a population of 105 million of which about 28% were infected with influenza resulting in about 650,000 deaths. India was hit particularly hard where 5% of the population, or about 14 million people, died.


San Francisco barber shop held outdoors in 1918. (source Wikipedia)

So, what happened to H1N1, the virus responsible for the 1918 Influenza Pandemic? While the pandemic officially ended in 1920, the virus is still around today. It made a global comeback in 1977 being dubbed the “Russian flu” because it was first identified in the Soviet Union. It went around the world for two years leading to about 700,000 deaths before fading again. It returned in January 2009 as the “Swine flu”, again traveling around the world for two years resulting in 284,000 deaths.


It appears that for similar respiratory viruses, the pattern of traveling around the world for about two years before fading is common. This occurred with each of the influenza outbreaks described above. It also happened with SARS-1, which is closely related to SARS-2, the virus that causes COVID. SARS-1 is a virus that also appears to have originated in bats and hopped to humans in China. It caused a global outbreak between 2002 and 2004, producing an illness very similar to COVID, but with a much higher mortality rate. Based on these similar patterns, it seems reasonable to expect that COVID will last perhaps another year before fading. Unlike these others, however, the worldwide vaccination efforts are very likely to shorten this dramatically. While the pandemic will eventually end, the virus will still be around, just not causing widespread illness like now.


For a while now scientists, public health experts and the World Health Organization have been urging being prepared for future pandemics. They pointed out that we were due for another big epidemic and one study, published in 2014 predicted another global pandemic on the size of the 1918 pandemic before 2040. A study, published in 2007 by Vincent Cheng and others in the journal Clinical Microbiology Reviews stated, "the presence of a large reservoir of SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern China, is a time bomb. The possibility of the reemergence of SARS and other novel viruses from animals or laboratories and therefore the need for preparedness should not be ignored". Of course, that is exactly what happened.


In 2014, President Obama formed the Directorate for Global Health Security and Biodefense within the National Security Council. Its mission was to prepare the US for the next disease outbreak and prevent it from becoming an epidemic or pandemic. This Directorate was dissolved by President Trump in May 2018. Looking at how slow and disorganized America’s response was to COVID, one wonders how much things could have been different had we stayed prepared.

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