Poliomyelitis leading to large-scale trials in the then Belgian Congo and the vaccination of seven million children in Poland against serotypes PV1 and PV3 between 1958 and 1960. The second inactivated polio virus vaccine was developed in 1952 by Jonas Salk at the University of Pittsburgh, and announced to the world on 12 April 1955. The Salk vaccine, or inactivated poliovirus vaccine, is based on poliovirus grown in a type of monkey kidney tissue culture (vero cell line), which is chemically inactivated with formalin. After two doses of inactivated poliovirus vaccine (given by injection), 90 percent or more of individuals develop
Jonas Salk ... who read everything he could lay his hands on," according to one of his fellow students. Students had to cram a four-year curriculum into just three years. As a result, most dropped out or flunked out, despite the school's motto "study, study, study." Of the students who graduated, however, most would have the grades to enroll in CCNY, noted for being a highly competitive college. Salk enrolled in CCNY from which he earned a Bachelor of Science degree in chemistry in 1934. Oshinsky writes that "for working-class immigrant families, City College represented the apex of public higher education. Getting