What can we learn from the 1918 flu pandemic?

By Julia Sobolik, MS MPH and Brad Kern, PhD

A little over a century ago, the 1918 influenza (flu) pandemic ravaged the globe. The 1918 flu infected roughly 500 million people and probably killed more than 50 million. That pandemic holds lessons about viral transmission pathways, control measures, and epidemiology, all of which we can use today.

Transmission pathways: While the 1918 flu pandemic was caused by a different bug than the one that causes COVID-19, both viruses are transmitted through droplets. Virus-containing droplets spread when an infected person coughs or sneezes, and possibly even when that person exhales. Understanding this similarity in viral transmission can inform control measures (e.g., face coverings) and strategies to reduce infection risk (e.g., social distancing and self-quarantining) in the current pandemic.

Control Measures: During the 1918 pandemic, we used now-familiar control measures—social distancing, face coverings, isolating infected people, and closing schools, churches, and theaters. Back then, these measures had some success in reducing deaths. Of course, medicine has advanced a lot since the early 1900s. But our options are still limited while we wait for a vaccine and/or treatments to address this new virus. Until a vaccine (or an effective treatment) is ready and accessible to everyone, we must again use control measures to slow down this pandemic.

Epidemiology: Tracking the spread of the 1918 pandemic can inform our approach to this one. Beginning in 1918, three waves of infections hit the U.S. over two years. While the first wave looked like a bad flu season, the second and third were far deadlier. The later waves were likely caused by several factors—WWI vets returning home from Europe, infected people traveling between communities, and inconsistencies in the timing and type of control measures we used. One 2007 study of the 1918 pandemic found that some cities had low death rates in the first wave but far more severe death rates in the later waves. This was especially true when cities lifted control measures too early. On this point, another study found that U.S. cities that lifted interventions too soon reduced the overall effectiveness of those interventions, even if they worked at first. A study of the 1918 pandemic in Sydney, Australia, concluded that social distancing reduced people's contact with infected persons by up to 38%. 

Today, we must strive to prevent multiple waves of COVID-19 cases. Lessons from 1918 teach that we must maintain social distancing, wear face coverings, and self-isolate after exposure, especially as states gradually open and lift restrictions.


Last update: July 11, 2020, 10:39pm ET

Science review: ARM, ERS