Cold War tensions and the polio vaccine Sabin vaccine from the Soviet side. However other Soviet virologists argued that the Salk vaccine could be considered safe, since the Americans tested it on their own people. They considered that the Sabin vaccine must be potentially dangerous because the Americans did not wish to test it on their own society. The documented achievement of the Sabin-Chumakov collaboration eventually trumped the ideological differences of the Cold War. Their oral live-virus vaccine became federally licensed in 1962, and used for over three decades to help eliminate polio globally, replacing the Salk vaccine. Using these vaccines, the threat of polio remains only
Polio vaccine attenuate the Sabin 2 strain, and 10 substitutions are involved in attenuating the Sabin 3 strain. The primary attenuating factor common to all three Sabin vaccines is a mutation located in the virus's internal ribosome entry site, which alters stem-loop structures, and reduces the ability of poliovirus to translate its RNA template within the host cell. The attenuated poliovirus in the Sabin vaccine replicates very efficiently in the gut, the primary site of infection and replication, but is unable to replicate efficiently within nervous system tissue. In 1961, type 1 and 2 monovalent oral poliovirus vaccine (MOPV) was licensed, and