History of animal testing moment antibiotics were introduced, the fall became steep so that by the 1980s mortality in developed countries was effectively zero. In the 1940s, Jonas Salk used rhesus monkey cross-contamination studies to isolate the three forms of the polio virus that affected hundreds of thousands yearly. Salk's team created a vaccine against the strains of polio in cell cultures of rhesus monkey kidney cells. The vaccine was made publicly available in 1955 and reduced the incidence of polio 15-fold in the USA over the following five years. Albert Sabin made a superior "live" vaccine by passing the polio virus through animal
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