Albert Sabin and prove its extraordinary effectiveness and safety. The Sabin vaccine worked in the intestines to block the poliovirus from entering the bloodstream. In the intestines, Sabin had discovered, the poliovirus multiplied and attacked. Thus, the oral vaccine broke the chain of transmission of the virus and allowed for the possibility that polio might one day be eradicated. Between 1955 and 1961, the oral vaccine was tested on at least 100 million people in the USSR, parts of Eastern Europe, Singapore, Mexico, and the Netherlands. The first industrial production and mass use of oral poliovirus vaccine (OPV) from Sabin strains was
Polio vaccine testing outside the United States, Sabin in Mexico and then in the Soviet Union, and Koprowski in the Congo and Poland. In 1957, Sabin developed a trivalent vaccine, containing attenuated strains of all three types of poliovirus. In 1959, ten million children in the Soviet Union received the Sabin oral vaccine. For this work, Sabin was given the medal of the Order of Friendship Among Peoples, described as the Soviets' highest civilian honor, despite having become an American during the height of the cold war. Sabin's oral vaccine using live virus came into commercial use in 1961. Once Sabin’s oral