Robert McCollum, a viral researcher, has died, reports the New York Times. He was 85. McCollum was part of a team at Yale University in the 1950s that discovered that the polio virus circulated in the blood before entering the spinal column — a finding that paved the way for a vaccine, the Times notes. McCollum then studied hepatitis and was able to tell the difference between serum hepatitis from transfusions and infectious hepatitis. That work became controversial with accusations it was performed on mentally retarded children, though the main critic later said the work was done properly, the Times adds. McCollum moved on to become dean of Dartmouth Medical School. "Bob made substantive contributions to our understanding and the prevention of viral diseases that affect millions of people globally," Dartmouth's John Modlin says.