In 1919, the Treaty of Versailles was signed. Which global pandemic was still spreading?

The story behind the answer

The Spanish flu is correct because the devastating 1918–1920 influenza pandemic was still raging in 1919, overlapping with the Paris Peace Conference and the signing of the Treaty of Versailles. Multiple waves struck worldwide, with soldiers’ demobilization and crowded celebrations helping spread the virus. It killed an estimated 50 million people—far more than World War I.

Despite its name, the “Spanish” flu didn’t start in Spain; neutral Spain’s