n 1918 and 1919, the novel H1N1 “Spanish flu” virus killed between 50 million and 100 million people—as much as 5 percent of the world's population—mostly within a few months, making the contemporaneous mass murder of World War I look like a bagatelle. The pandemic was, Laura Spinney writes in her book Pale Rider: The Spanish Flu of 1918 and How It Changed the World, “the greatest tidal wave of death since the Black Death, perhaps in the whole of human history.”
