Thomas Francis Jr. (July 15, 1900 – October 1, 1969) was an American physician, virologist, and epidemiologist who guided the discovery and development of the polio vaccine being worked on by his student Jonas Salk.

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.

Conducted by a staff of more than 100 people from the University of Michigan, the year-long trial involved 1.8 million children in the U.S., Canada, and Finland and an enormous network of community volunteers.

The results of the study were announced in Rackham Auditorium of the University of Michigan on April 12, 1955, and signaled an era of hope and success in combating infectious diseases and, more broadly, in the development of large-scale efforts for the good of society.

Of his work, Francis remarked: "Epidemiology must constantly seek imaginative and ingenious teachers and scholars to create a new genre of medical ecologists who, with both the fine sensitivity of the scientific artist, and the broad perception of the community sculptor, can interpret the interplay of forces which result in disease."