In 1954, the vaccine was tested for its ability to prevent polio; the field trials involving the Salk vaccine would grow to be the largest medical experiment in history.
The result was a substantial reduction in the number of poliomyelitis cases, even from the much reduced levels following the introduction of the Salk vaccine.
The Salk vaccine was an inactivated polio virus, which when injected into a human would mount an immune response and so provide individual protection against wild polio.
