Enders, the son of a wealthy banker from West Hartford in Connecticut, was educated at Yale and Harvard where he obtained his PhD in 1930. His career was somewhat delayed by the war, in which he served as a flying instructor, and also by his initial intention to study Germanic and Celtic languages. This was upset by the influence of the bacteriologist Hans Zinsser who ‘seduced’ Enders into science in the late 1920s.

In 1946 Enders set up an Infectious Diseases Laboratory at the Boston Children's Hospital; it was here that he did the work to be later described as opening up a “new epoch in the history of virus research.” This referred to his success, in collaboration with Thomas Weller and Frederick Robbins, in 1949 in cultivating polio virus in test tube cultures of human tissue for the first time. They further demonstrated that the virus could be grown on a wide variety of tissue and not just nerve cells.

This at last allowed the polio virus to be studied, typed, and produced in quantity. Without such an advance the triumphs of Albert Sabin and Jonas Salk in developing a vaccine against polio in the 1950s would have been impossible. In 1954 Enders, Weller, and Robbins were awarded the Nobel Prize for physiology or medicine.

By this time Enders had already begun to work on the cultivation of the measles virus. This time, working with T. Peebles, they followed up their success in cultivating the virus with, in 1957, the production of the first measles vaccine.