Twenty-eighteen has a number of anniversaries marking big events in history. A century ago women got the vote, World War I ended, but the worst pandemic in history began, the Spanish flu. Even though we've learned much about it, the reality is the tragedy could happen again.

One-third of the world contracted this influenza and between fifty and one hundred million people died. That's more than those killed in World War One and the virus shaped history in other ways. For example, the mishandling of the pandemic in India boosted their independence movement. The Spanish flu spared no one. Among those infected who survived were the British prime minister, the American President, and the German Kaiser.

This virus was also different in that it was most deadly for people ages twenty to forty instead of the very young and old. Despite its name, the flu did not originate in Spain. When world war one was winding down, reports of a deadly flu came out of several countries including Spain. It spread along trade routes and the mass movement of soldiers also helped spread it across nearly every continent.

In the US, by October nineteen eighteen, almost two hundred thousand people had died. Gauze masks were distributed, quarantines instituted, store sales were banned, theaters closed, funerals were limited to fifteen minutes, and health certificates were required by the railways and to enter some towns. There weren't enough grave diggers to bury the dead. By the summer of nineteen nineteen, the pandemic ended after those infected either died or became immune.

Today scientists keep a constant vigil for the next possible flu strain to spark a pandemic.