On March 26, 1953, University of Pittsburgh scientist Jonas Salk announced that he was testing a polio vaccine. Salk’s vaccine prevented those who took it from coming down with polio, one of the worst epidemics of the 20th century. Polio is very contagious, and spreads easily. It often paralyzes or cripples victims, and children are most vulnerable.

By the time Salk tested his vaccine, there were more than 35,000 cases of polio reported in the U.S. every year. The vaccine interrupted the spread of polio, and by the 21st century polio had been eradicated in much of the world.

Noun

outbreak of an infectious disease able to spread rapidly.

eradicate
Verb

to destroy or remove.

paralyze
Verb

to prevent movement.

vulnerable
Adjective

capable of being hurt.