Polio vaccine attenuated vaccine strains. In 1958, the National Institutes of Health created a special committee on live polio vaccines. The various vaccines were carefully evaluated for their ability to induce immunity to polio, while retaining a low incidence of neuropathogenicity in monkeys. Large-scale clinical trials performed in the Soviet Union in late 1950s to early 1960s by Mikhail Chumakov and his colleagues demonstrated safety and high efficacy of the vaccine. Based on these results, the Sabin strains were chosen for worldwide distribution. Fifty-seven nucleotide substitutions distinguish the attenuated Sabin 1 strain from its virulent parent (the Mahoney serotype), two nucleotide substitutions
Albert Sabin humanitarian benefit. Indeed, it was not clear to many that the vaccine was an American one, financed by U.S. dollars, as it was not widely available to ordinary Americans. Sabin also developed vaccines against other viral diseases, including encephalitis and dengue. In addition, he investigated possible links between viruses and some forms of cancer. In 1983, Sabin developed calcification of the cervical spine, which caused paralysis and intense pain. Sabin revealed in a television interview that the experience had made him decide to spend the rest of his life working on alleviating pain. This condition was successfully treated by surgery