Jonas Salk vaccine. A few weeks later, Salk injected children at the Polk State School for the retarded and feeble-minded. In 1954 he tested the vaccine on about one million children, known as the polio pioneers. The vaccine was announced as safe on April 12, 1955. The project became large, involving 100 million contributors to the March of Dimes, and 7 million volunteers. The foundation allowed itself to go into debt to finance the final research required to develop the Salk vaccine. Salk worked incessantly for two and a half years. Salk's inactivated polio vaccine was the first vaccine for the disease;
Jonas Salk the University of Michigan. Francis had recently joined the faculty of the medical school after working for the Rockefeller Foundation, where he had discovered the type B influenza virus. According to Bookchin, "the two-month stint in Francis's lab was Salk's first introduction to the world of virology—and he was hooked." After graduating from medical school, Salk began his residency at New York's prestigious Mount Sinai Hospital, where he again worked in Francis's laboratory. In 1947, Salk became ambitious for his own lab and was granted one at the University of Pittsburgh School of Medicine, but the lab was smaller than