Spanish Flu

The 1918 influenza pandemic (January 1918 – December 1920; colloquially known as Spanish flu) was an unusually deadly influenza pandemic, the first of the two pandemics involving H1N1 influenza virus. It infected 500 million people around the world, including people on remote Pacific islands and in the Arctic. Probably 50 million, and possibly as high as 100 million (three to five percent of Earth's population at the time) died, making it one of the deadliest epidemics in human history.