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
The Heroic Age of American Invention The Heroic Age of American Invention The Heroic Age of American Invention is a 1961 science book for children by L. Sprague de Camp, published by Doubleday. It was reprinted in 1993 by Barnes & Noble under the title "Heroes of American Invention". By "heroic age" the author means the era of American history in which individual initiative and enterprise constituted the primary thread in technical innovation, roughly from the early 19th century until mass production and corporate enterprise outpaced that of the individual around the time of World War I. The story of innovation is told through the biographies