Image: Red Cross Nurses at Salisbury, North Carolina on Christmas Day, 1918
One of the most deadly pandemics in modern history took place during World War I, from 1918 to 1919. Nearly one-third of the planet's population became infected with this horrible sickness, resulting in life expectancy dropping by over 10 years. The virus killed an estimated 20 to 50 million victims, with over 670,000 of them being American.
First discovered in the United States, Europe and parts of Asia, the flu quickly spread around the world, with many of the victims being healthy, young adults, surprisingly. Vaccines and flu prevention medicine like Tamiflu weren't around 100 years ago, so many Americans took to wearing masks in public places, such as schools and theatres.
Numerous businesses were forced to close, due to so many employees being infected. Mail delivery and garbage pick-up were supremely halted. Even health departments and hospitals closed up shop, only adding to the nightmare.
Image: This Red Cross veil, from Wilmington, NC, was worn in 1918 during the WW1 flu pandemic that killed over 600,000 Americans.
People who caught this vicious virus often died within hours or days of symptoms appearing, their lungs rapidly filling with fluid, causing them to suffocate. Historian and author Alfred Crosby has been quoted as saying the virus "killed more humans than any other disease in a period of similar duration in the history of the world."
By the summer of 1919, the flu virus finally came to an end. The infected either built up an immunity or, more likely, (and sadly) mortally succumbed to the disease. Per History.com, in 2008, "researchers announced they'd discovered what made the 1918 flu so deadly: A group of three genes enabled the virus to weaken a victim's bronchial tubes and lungs and clear the way for bacterial pneumonia."