Polio vaccine The results of the field trial were announced 12 April 1955 (the tenth anniversary of the death of President Franklin D. Roosevelt, whose paralytic illness was generally believed to have been caused by polio). The Salk vaccine had been 60–70% effective against PV1 (poliovirus type 1), over 90% effective against PV2 and PV3, and 94% effective against the development of bulbar polio. Soon after Salk's vaccine was licensed in 1955, children's vaccination campaigns were launched. In the U.S, following a mass immunization campaign promoted by the March of Dimes, the annual number of polio cases fell from 35,000 in 1953
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