In 1947, a story by the Associated Press reported good news in the fight against polio. An early experiment was performed at Johns Hopkins University, where monkeys were injected with a low dose of the vaccine and given time to develop antibodies. They showed no symptoms of a disease later when exposed to concentrations “thousands of times more deadlier than anything a man might pick up naturally.” This early experiment, and others like it in Europe, paved the way for the first truly effective one made by Dr. Jonas Salk.

On this day, April 12, in 1955, after successful field trials of the vaccine, the monitor of the test results, Dr. Thomas Francis, Jr., of the University of Michigan, declared it “safe and effective.”

Just three years earlier, a polio outbreak in the United States afflicted over 50,000 children. News of a Polio vaccine was understandably shattering. Reports from contemporary sources had people openly tearing up with joy, with churches ringing bells in celebration. Politicians interrupted conferences to announce the news and thank Dr. Salk. The Eisenhower White House prepared to award him a medal as a “benefactor of mankind.”