1955

In the face of a devastating polio epidemic, Jonas Salk believed that a vaccine with a “killed” polio virus could safely immunize without the risk of infection. In 1955, it was announced that Salk’s poliovirus vaccine was 80-90% effective against paralytic polio. Upon adoption of the vaccine, the average number of polio cases in the U.S. dropped from more than 45,000 to just 910. It is unlikely, however, that Salk was surprised by this success. His confidence in the protective powers of his vaccine was so high that, two years earlier, he had administered the vaccine to himself, his wife and their three sons.