-
Fewer Cases in Late 30s
In the late thirties, there were fewer cases of polio than in 1956. -
Rise of Cases
There was a rise in the early 1940s, particularly in 1944 when 19,029 cases were reported. -
Drop to 10,000 Polio Cases
A sharp drop to about 10,000 cases in 1947. -
"High Polio Years"
In 1952, there were a number of "high polio years" reaching a peak with 57,879 cases. -
Polio Vaccine Trials Begin
On this day in 1954, the Salk polio vaccine field trials, involving 1.8 million children, begin at the Franklin Sherman Elementary School in McLean, Virginia. Children in the United States, Canada and Finland participated in the trials, which used for the first time the now-standard double-blind method, whereby neither the patient nor attending doctor knew if the inoculation was the vaccine or a placebo. -
Drop-off of Half the Cases Cases in 1952
Drop-off to about half that number of cases in 1952 in 1955. -
Salk Vaccine Announced Safe and Effective
On April 12, 1955, researchers announced the vaccine was safe and effective and it quickly became a standard part of childhood immunizations in America. In the ensuing decades, polio vaccines would all but wipe out the highly contagious disease in the Western Hemisphere.
