In the 1940s and 1950s, polio was a big problem, especially for children. πΆ
Salk believed he could help fight this disease. He started working on a vaccine, a special
medicine that helps protect people from getting sick. Salk used a killed version of the virus to create the vaccine, which is very safe. In 1955, after testing it on thousands of volunteers, the vaccine was declared safe and effective! π
It was a huge success and many children got vaccinated, which helped to nearly wipe out polio in many countries.