360The Salk polio vaccine is declared safe and effective
On 12 April 1955, scientists announced that Jonas Salk's polio vaccine was safe and effective, after a trial involving about 1.8 million children in the United States. Polio had paralysed tens of thousands of children every year. Vaccination began at once. With Albert Sabin's oral vaccine and a global campaign, wild polio now survives in only two countries.
Polio is a virus that can attack the nerves and cause paralysis. In the early 1950s, epidemics in the United States paralysed thousands of children every summer, and parents kept children away from swimming pools.
Jonas Salk, at the University of Pittsburgh, developed a vaccine using virus that had been killed with chemicals. In 1954 it was tested in one of the largest medical trials in history, with about 1.8 million children, the 'Polio Pioneers'.
On 12 April 1955, the trial's director, Thomas Francis, announced the vaccine worked. Church bells rang across America. Asked who owned the patent, Salk said: 'Well, the people, I would say.'
Albert Sabin's oral vaccine followed in the early 1960s. The Global Polio Eradication Initiative, launched in 1988, has reduced cases by more than 99%.
- 1952
- A severe polio epidemic in the United States
- 1954
- The Salk vaccine trial
- 12 April 1955
- The vaccine is declared safe and effective
- 1988
- The global eradication campaign begins
Sources: World Health Organization · Smithsonian · Britannica.