Britannica Sources used in this answer

How many children took part in the Francis Field Trial of the Salk vaccine?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Polio vaccine — polio A health care worker giving a polio vaccine to a child in Katsina state, Nigeria, 2014.

The Francis Field Trial, a massive nationwide test of the Salk vaccine conducted in 1954–55, involved 1.8 million children in the first, second, and third grades across the United States.1