Albert Sabin - Wikipedia

On October 6, 1956, Dr Albert Sabin discovers oral polio vaccine. From the article:

"With the menace of polio growing, Sabin and other researchers, most notably Jonas Salk in Pittsburgh and Hilary Koprowski and Herald Cox in New York City and Philadelphia, sought a vaccine to prevent or mitigate the illness. The Sabin vaccine is an oral vaccine containing weakened forms of strains of polio viruses. In 1955, Salk's "killed" vaccine was released for use. It was effective in preventing most of the complications of polio, but did not prevent the initial intestinal infection. The Sabin vaccine is easier to give than the earlier vaccine developed by Salk in 1954, and its effects last longer. Sabin first tested his live attenuated oral vaccine at the Chillicothe Ohio Reformatory in late 1954. From 1956–1960, he worked with Russian colleagues to perfect the oral vaccine and prove its extraordinary effectiveness and safety. The Sabin vaccine worked in the intestines to block the poliovirus from entering the bloodstream. In the intestines, Sabin had discovered, the poliovirus multiplied and attacked. Thus, the oral vaccine broke the chain of transmission of the virus and allowed for the possibility that polio might one day be eradicated.

Between 1955 and 1961, the oral vaccine was tested on at least 100 million people in the USSR, parts of Eastern Europe, Singapore, Mexico, and the Netherlands. The first industrial production and mass use of oral poliovirus vaccine (OPV) from Sabin strains was organized by Soviet scientist Mikhail Chumakov.[6][7] This provided the critical impetus for allowing large-scale clinical trials of OPV in the United States in April 1960 on 180,000 Cincinnati school children. The mass immunization techniques that Sabin pioneered with his associates effectively eradicated polio in Cincinnati. Against considerable opposition from the March of Dimes Foundation, which supported the relatively effective killed vaccine, Sabin prevailed on the Public Health Service to license his three strains of vaccine. While the PHS stalled, the USSR sent millions of doses of the oral vaccine to places with polio epidemics, such as Japan, and reaped the humanitarian benefit. Indeed, it was not clear to many that the vaccine was an American one, financed by U.S. dollars, as it was not widely available to ordinary Americans.

Sabin also developed vaccines against other viral diseases, including encephalitis and dengue. In addition, he investigated possible links between viruses and some forms of cancer."