April 12, 1955: The Day That Changed History - 'Safe, Effective, and Potent'
What Three Words Ended America’s Polio Terror on April 12, 1955?
“Safe, effective, and potent.” With these words at 10:20 AM EST on April 12, 1955, Dr. Thomas Francis Jr. announced to the world from University of Michigan’s Rackham Auditorium that the Salk polio vaccine was 80-90% effective in preventing paralytic polio. This historic announcement, based on trials involving over 1.8 million children, immediately ended America’s greatest childhood health terror.