American Jewish doctor and medical researcher born in New York who developed the first safe and effective vaccine for polio. In 1963 he became director of the Salk Institute for Biological Research at Univ. California, San Diego. He developed a vaccine against polio by growing the three virus strains separately in monkey tissue. The virus was removed from the tissue, stored for a week, killed with formaldehyde, and tested to make sure it died. A series of three or four injections with the killed virus vaccine were required to immunize.