In 1918, the world experienced its last major pandemic: the outbreak of the “Spanish flu.” It was the deadliest pandemic in human history in terms of the per-capita mortality rate. As many as 50 million people died during that pandemic—around two percent of the world’s population, and five times more deaths than the entire First World War that had preceded it.

By these metrics, the COVID-19 virus, which is far less dangerous than the Spanish flu on an individual level, is lagging far behind. Around 4.5 million people have died to date of the virus, a small fraction of the 1918 pandemic’s mortality rate—and far smaller when considering that the world population is significantly higher today than it was in 1918.

However, comparisons between the two arose after the U.S. passed a tragic milestone: according to data collected by Johns Hopkins University, more than 675,000 Americans have now died of the COVID-19 virus, surpassing the number of deaths in the United States during the 1918 pandemic.

Experts have warned that the Spanish flu and COVID-19 are not easily comparable. During the century separating the two pandemics, significant medical advancements have helped to treat many victims of the coronavirus—the most important of which has been the vaccine, which decreases one’s chances of dying of COVID-19 to statistical insignificance.

Still, some similarities persist. Both pandemics involved substantial school and business closures and quarantining. Moreover, the use of masks became widespread during the Spanish flu—as did the first mask mandates.

Ultimately, 500 million people—more than one-fourth of the world’s population at the time—were estimated to have been infected by the Spanish flu. This number is guesswork, as sophisticated medical surveying did not yet exist at the beginning of the twentieth century. While present-day methods have improved somewhat, shortcomings continue to exist; inconsistent reporting among states and local areas has led some experts to believe that the current coronavirus death count could be somewhat higher than has been reported.

It is estimated that the Spanish flu’s mortality rate was roughly 2.5 percent, compared to COVID-19’s roughly 1.6 percent for unvaccinated people (and negligible for vaccinated people). In comparison, a normal seasonal flu has a mortality rate of less than 0.1 percent.

The population of the United States in 1918 was just over 100 million, compared to roughly 330 million today.

Trevor Filseth is a current and foreign affairs writer for the National Interest.

Image: Flickr