Albert Sabin a vaccine to prevent or mitigate the illness. The Sabin vaccine is an oral vaccine containing weakened forms of strains of polio viruses. In 1955, Salk's "killed" vaccine was released for use. It was effective in preventing most of the complications of polio, but did not prevent the initial intestinal infection. The Sabin vaccine is easier to give than the earlier vaccine developed by Salk in 1954, and its effects last longer. Sabin first tested his live attenuated oral vaccine at the Chillicothe Ohio Reformatory in late 1954. From 1956–1960, he worked with Russian colleagues to perfect the oral vaccine
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