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 in the U.S. Army Medical Corps and helped develop a vaccine against Japanese encephalitis. Maintaining his association with Children's Hospital, by 1946, he had also become the head of Pediatric Research at the University of Cincinnati. At Cincinnati's Children's Hospital, Sabin supervised the fellowship of Robert M. Chanock, whom he called his "star scientific son." Sabin went on a fact-finding trip to Cuba in 1967 to discuss with Cuban officials the possibility of establishing a collaborative relationship between the United States and Cuba through their respective national academies of sciences, in spite of the fact that the two countries did