Dr. Jonas Salk developed a vaccine for which virus in 1955?

Jonas Edward Salk (/sɔːlk/; October 28, 1914 – June 23, 1995) was an American medical researcher and virologist. He discovered and developed one of the first successful polio vaccines. Born in New York City, he attended New York University School of Medicine, later choosing to do medical research instead of becoming a practicing physician. In 1939, after earning his medical degree, Salk began an internship as a scientist physician at Mount Sinai Hospital. Two years later he was granted a fellowship at the University of Michigan, where he would study flu viruses with his mentor Thomas Francis, Jr.

Until 1955, when the Salk vaccine was introduced, polio was considered one of the most frightening public health problems in the world. In the post war United States, annual epidemics were increasingly devastating. The 1952 U.S. epidemic was the worst outbreak in the nation's history. Of nearly 58,000 cases reported that year, 3,145 people died and 21,269 were left with mild to disabling paralysis, with most of its victims being children.