As we head into the Northern Hemisphere fall with covid-19 still raging in the US and a number of other parts of the world, two data points provide cause for extra concern.
One is that the seasonal flu—a respiratory viral infection like covid-19—is much more active in the winter. Last year in the US, there were 40 times as many flu cases in the fall and winter months as in the previous spring and summer. Historically, those cooler months see tens of times as many seasonal flu infections in temperate regions. (In tropical regions, the flu tends to peak during the rainy season, though not as strongly.)
Image: Clerks in New York City wore masks during the 1918 flu pandemic. NATIONAL ARCHIVES