1953

First inactivated polio vaccine created by Dr. Jonas Salk

The first inactivated polio vaccine (known as IPV) was created by Dr. Jonas Salk. Human trials began in 1954, and by 1955, Salk’s vaccine was available throughout the US. The incidence of paralytic polio decreased dramatically between 1954 and 1961. However, the antibodies wore off within a few years of this iteration of the vaccine and a large number of monkeys (1500 per 1 million doses) had to be sacrificed to obtain the kidney cells used to grow the virus.