............for probably ten years. This weekend seemed like a good time to dust it off and begin reading it:
Lewis was correct. In 1918 an influenza virus emerged—probably in the United States—that would spread around the world, and one of its earliest appearances in lethal form came in Philadelphia. Before that world-wide pandemic faded away in 1920, it would kill more people that any other outbreak of disease in human history. Plague in the 1300s killed a far larger percentage of the population—more than one-quarter of Europe—but in raw numbers influenza killed more than plague then, more than AIDS today.
The lowest estimate of the pandemic's worldwide death toll is twenty-one million, in a world with a population less than one-third today's. That estimate comes from a contemporary study of the disease and newspapers have often cited it since, but it is almost certainly wrong. Epidemiologists today estimate that influenza likely caused at least fifty million deaths world-wide, and possibly as many as one hundred million.