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 50,000 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.
Term Part of Speech Definition Encyclopedic Entry epidemic Noun
outbreak of an infectious disease able to spread rapidly.
to destroy or remove.
to prevent movement.
capable of being hurt.