Thomas Francis Jr. (July 15, 1900 October 1, 1969) was an American physician, virologist, and epidemiologist who guided the discovery and developement of the polio vaccine being worked on by his student Jonas Salk. Francis was the first person to isolate influenza virus in the United States, and in 1940 showed that there are other strains of influenza, and took part in the development of influenza vaccines. Life Francis grew up in New Castle in western Pennsylvania, graduated from New Castle High School in 1917 and Allegheny College on scholarship in 1921, and received his medical degree from Yale University in 1925. Afterwards he joined an elite research team at the Rockefeller Institute, first doing research on vaccines against bacterial pneumonia, later he took up influenza research. He became the first American to isolate human flu virus. From 1938 to 1941 he was professor of bacteriology and chair of the department of the New York University College of Medicine. In 1941 he was appointed director of the Commission on Influenza of the Armed Forces Epidemiological Board (AFEB), a position which enabled him to take part in the successful development, field trial, and evaluation of protective influenza vaccines. Later that year Francis received an invitation from Henry F. Vaughan to join the newly established School of Public Health at the University of Michigan. At the University of Michigan, Francis established a virus laboratory and a Department of Epidemiology that dealt with a broad range of infectious diseases. When Jonas Salk came to that university in 1941 to pursue postgraduate work in virology, Francis was his mentor and taught him the methodology of vaccine development. During this time at the University of Michigan, Francis and Salk, along with other researchers, deliberately infected patients at several Michigan mental institutions with the influenza virus by spraying the virus into their nasal passages. Salk's work at Michigan ultimately led to his polio vaccine. In 1947 Francis was awarded one of the first Michigan distinguished professorships, the Henry Sewall University Professor of Epidemiology. In addition to his work at the School of Public Health, Francis joined the pediatrics faculty at the University's Medical School. As director of the University of Michigan Poliomyelitis Vaccine Evaluation Center, Francis designed and led an unprecedented $17.5 million nationwide field trial to test the vaccine. Conducted by a staff of more than 100 people from the University of Michigan, the year-long