Jonas Edward Salk (October 28, 1914 - June 23, 1995) was an American medical researcher and virologist. He attended New York University School of Medicine, later choosing to do medical research instead of becoming a practicing physician. In 1948, he undertook a project funded by the National Foundation for Infantile Paralysis to determine the number of different types of polio virus. Salk saw an opportunity to extend this project towards developing a vaccine against polio, and, together with the skilled research team he assembled, devoted himself to this work for the next seven years. The field trial set up to test the Salk vaccine involved 20,000 physicians and public health officers, 64,000 school personnel, and 220,000 volunteers. Over 1,800,000 school children took part in the trial. When news of the vaccine's success was made public on April 12, 1955, Salk was hailed as a "miracle worker". His sole focus had been to develop a safe and effective vaccine as rapidly as possible, with no interest in personal profit. When asked who owned the patent to it, he said, "Well, the people I would say. There is no patent. Could you patent the sun?" Salk died from heart failure at the age of 80 in 1995. No photographer credited, undated.