Polio vaccine vaccine became widely available, it supplanted Salk’s injected vaccine, which had been tarnished in the public's opinion by the Cutter incident, in which Salk vaccines prepared by one company resulted in several children dying or becoming paralyzed. An enhanced-potency IPV was licensed in the United States in November 1987, and is currently the vaccine of choice there. The first dose of polio vaccine is given shortly after birth, usually between 1 and 2 months of age, and a second dose is given at 4 months of age. The timing of the third dose depends on the vaccine formulation, but should
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