Whose work led to the first successful polio vaccine?

Jonas Salk developed the first effective polio vaccine, which was licensed in 1955 after large-scale trials involving about 1.8 million children in the United States. The vaccine used killed poliovirus to stimulate immunity. It was a major breakthrough in public health and sharply reduced polio cases in many countries. Salk refused to patent the vaccine, saying the public should benefit freely.