“Influenza has a long history of devastating epidemics throughout human history, most notably the 1918 Spanish Flu pandemic which infected a large portion of the world’s population and caused millions of deaths; today, the influenza vaccine is crucial because the virus constantly mutates, requiring annual vaccination to prevent widespread outbreaks and reduce the severity of illness in individuals, especially those at high risk of complications. The flu pandemic lasts from 1918 to 1920. From spring of 1918 to spring of 1919, the flu causes more than 550,000 deaths in the U.S. and more than 20 million deaths worldwide.

In the fall of 1918 at Mayo Clinic, people with the flu and other contagious illnesses are cared for in the isolation hospital. Keeping patients with these illnesses isolated and keeping high standards of cleanliness likely prevented infections and saved lives.

 From 2020 Flu vaccines prevent about 7.5 million illnesses, 3.7 million doctor visits, 105,000 hospital stays and 6,300 deaths.”

MAYO CLINIC (https://www.mayoclinic.org/diseases-conditions/history-disease-outbreaks-vaccine-timeline/flu)