Near the start of the 20th century, a mysterious and deadly virus terrified Americans, particularly infecting young kids: Polio. Correspondent Rita Braver looks at the scientific arsenal brought to combat the epidemic and develop a vaccine, and talks with documentary filmmaker Carl Kurlander ("The Shot Felt 'Round the World"); Dr. Paul Duprex, who is trying to replicate Dr. Jonas Salk’s success in his research for a vaccine for COVID-19; and Joanne Yager, who survived polio as a teenager and now, at 83, runs a support group for polio survivors in Arizona called Polio Epic Tucson. Air Date: May 3, 2020