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
Necessity is the mother of invention our invention." Jowett's translation is noted for injecting flowery, if not florid, language familiar to his Victorian era audience. Jowett himself, in "Plato's Republic: The Greek Text", Vol. III "Notes", 1894, p. 82, gives a literal translation of Plato as "our need will be the real creator," without the proverbial flourish. In an address to the Mathematical Association of England on the importance of education in 1917, Alfred North Whitehead argued that ""the basis of invention is science, and science is almost wholly the outgrowth of pleasurable intellectual curiosity."" and in contrast to the old proverb ""Necessity is the mother