evidence: The Spanish flu pandemic of 1918-1919 was the deadliest pandemic in world history, infecting some 500 million people across the globe—roughly one-third of the population—and causing up to 50 million deaths, including some 675,000 deaths in the United States alone. The disease, caused by a new variant of the influenza virus, was spread in part by troop movements during World War I. Though the flu pandemic hit much of Europe during the war, news reports from Spain weren’t subject to wartime censorship, so the misnomer "Spanish flu" entered common usage. With no vaccines or effective treatments, the pandemic caused massive social disruption: Schools, theaters, churches and businesses were forced to close, citizens were ordered to wear masks and bodies piled up in makeshift morgues before the virus ended its deadly worldwide march in early 1920. [...] Although the death toll attributed to the Spanish flu is often estimated at 20 million to 50 million victims worldwide, other estimates run as high as 100 million victims—around 3 percent of the world’s population. The exact numbers are impossible to know due to a lack of medical record-keeping in many places. [...] Fighting the Spanish Flu