Evans served as a public health officer in
Japan as part of his active duty service during
World War II, where he became interested in the work of epidemiologist
John R. Paul. He subsequently received a fellowship to study
infectious mononucleosis with Paul at Yale. During the
Korean War, he returned to active duty and served as chief of the Hepatitis Research Laboratory at the 98th General Hospital in
Munich,
Germany. In 1952, he became a professor at the
University of Wisconsin School of Medicine. He subsequently went on sabbatical leave to earn an MPH degree from the University of Michigan. Upon his return to the University of Wisconsin in 1959, he became the first chairman of the Department of Preventive Medicine. He became a professor of epidemiology at the
Yale School of Public Health in 1966. In 1982, he was appointed the John Rodman Paul Professor of Epidemiology at the Yale School of Medicine, a position he retained until he retired in 1994. At the Yale School of Medicine, he was also the director of their serum reference bank. ==Death==