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
Tukiki and His Search for a Merry Christmas given gifts which he eventually takes back to give to his selfish arctic friends. The thoughtful giving of gifts brings about a change in Tukiki's homeland and suddenly harmony reigns where once was none, and through Tukiki's act of love, the true meaning of Christmas is discovered. 1980 Genie Awards: "Tukiki and His Search for a Merry Christmas" was released on VHS by Embassy Home Entertainment in 1986 which has long been out of print. On August 12, 2008, it was released as a manufacture-on-demand DVD-R as part of the "Holiday Classics" series by Phoenix Learning Group, Inc. Tukiki and