In 1961, oral polio vaccine, developed by Dr. Albert Sabin, was licensed for use in the U.S. In 1957 Sabin convinced the Soviet Unionﾒs Health Ministry to conduct field studies with his vaccine. After the Soviet trial succeeded in 1960, the U.S. Public Health Service approved the vaccine in 1961 for manufacture in the U.S., and the World Health Organization (WHO) began to use live-virus vaccine produced in the USSR.

Sabin previously signed an agreement with Pfizer to produce the vaccine which was manufactured at its UK production facilities.