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
His Name Is Legs (Ladies and Gentlemen) before undertaking a much-anticipated North American tour with Ravi Shankar. With Peter Sellers among his entourage, Harrison alternatively adopted comedy and his Hindu-aligned spiritual goals as a defence against expectations related to his Beatle past during the tour.<ref name="Fong-Torres/2001">Ben Fong-Torres, "George Harrison: Harrison in the Haight", "San Francisco Chronicle", 2 December 2001; available at Rock's Backpages (subscription required).</ref> When discussing "His Name Is Legs" with BBC Radio 1 DJ Paul Gambaccini in September 1975, Harrison said that after recording the basic track, he invited Smith to sing the first two lines of each of the bridges. Smith did these vocal