Salk's Vaccine Declared Safe: Polio's Terror Ends
On April 12, 1955, Dr. Thomas Francis Jr. of the University of Michigan announced the results of the largest medical field trial in history: Jonas Salk's polio vaccine was safe, effective, and potent. The trial had involved 1.8 million children across 44 states. Church bells rang. Factory whistles blew. Parents wept. Polio had been the most feared disease in America, paralyzing an average of 35,000 children annually in the early 1950s. Salk became an instant national hero but refused to patent the vaccine, saying "Could you patent the sun?" He estimated this decision cost him $7 billion. Within two years of mass vaccination, US polio cases dropped 85-90%. The disease was effectively eliminated from the Western Hemisphere by 1994.
April 12, 1955
71 years ago
Key Figures & Places
What Else Happened on April 12
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