By the late 1940s, the National Institute of Infantile Paralysis had raised millions of dollars to pay for patient care and laboratory research. But polio cases were reaching record levels, and scientists were no closer to a cure. Frustrated by the slow progress, Basil O’Connor resolved to recruit fresh talent to the cause. He soon found what he was looking for in a young and energetic researcher named Jonas Salk. In 1951, Salk began testing a killed virus polio vaccine on monkeys in his Pittsburgh lab. His research soon put him at odds with the leading polio scientist Albert Sabin, who wanted his own live virus vaccine formula to prevail. As their rivalry escalated, Salk prepared to take the risky step of testing his vaccine on human subjects. Be the first to know about Wondery’s newest podcasts, curated recommendations, and more! Sign up now at https://wondery.fm/wonderynewsletter Listen to American History Tellers on the Wondery App or wherever you get your podcasts. Experience all episodes ad-free and be the first to binge the newest season. Unlock exclusive early access by joining Wondery+ in the Wondery App, Apple Podcasts or Spotify. Start your free trial today by visiting wondery.com/links/american-history-tellers/ now.