Polio vaccine 900 developed polio; in the group receiving the vaccine, only one out of 7,500 developed polio, making the vaccine 88% effective during the first year. However, other researchers believed that the one case was likely caused by the vaccine, and two more possible cases were reported later. After this meeting, Brodie, whose polio vaccine was at least partially effective and reasonably safe, and who developed several ground-breaking ideas about vaccination whose validity was confirmed two decades later with the development of the Salk vaccine, was immediately fired and had trouble finding employment again. Brodie died three and a half years
Cold War tensions and the polio vaccine flew to Leningrad in June, 1956. As a result of a cooperation of Sabin and Chumakov in Leningrad, Sabin was able to test his attenuated vaccine when funding in America was declined. While Sabin was working behind the Iron Curtain, the Sabin-Chumakov vaccine was determined to be safe and effective. Cold War tensions caused Western scientists to refuse the reports from the Russians about the effectiveness of the Sabin vaccine. However, mass vaccinations of Sabin's vaccine spread throughout Eastern Europe from 1960–1963. Just as some Soviet virologists did not trust the Western Salk vaccine, Americans had similar reservations about the