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
Lee Salk his older brother. Salk attended the University of Michigan. Salk's published work investigated the effect of retirement on mortality, the effect of the mother's heartbeat on the newborn, and the relationship between adverse maternal and perinatal conditions and later self-destructive behavior. He was the author of eight books. Salk was married twice, first to Kerstin and then Mary Jane. He had two children from his first marriage, a son Eric and daughter Pia. Salk developed cancer and died in hospital in Manhattan at age 65 on May 2, 1992. Salk was a professor at Cornell University Medical Center. Lee Salk