Following the conclusion of World War I and under the leadership of William Welch, Johns Hopkins University opened its School of Hygiene and Public Health, the first such institution in the United States. Wade Hampton Frost became its first professor of epidemiology.

Johns Hopkins was a wealthy, unmarried, Quaker, Baltimore businessman who viewed his wealth as carrying an obligation to serve humanity. He established and endowed corporations for Johns Hopkins University and Johns Hopkins Hospital, each with twelve directors (ten individuals served on both boards). To each he gave $3.5 million in 1867. From the start, he indicated that medical education was to be an important function of the university. Although his endowment did not specifically link the hospital to the university, there was never doubt in the minds of the trustees that they should be tightly associated.

William Henry Welch was a Connecticut Yankee, born in Norfolk, Connecticut, on April 8, 1850. He attended Yale University, where he studied the classics, a field in which he hoped to make his career as an academician. Failing to gain a faculty appointment, he studied chemistry at Yale and then medicine at the College of Physicians and Surgeons in New York City. After an internship at Bellevue Hospital in the same city, he joined the hospital’s department of pathology. Exciting things in medicine were taking place in Europe, and soon Welch was in Germany, where he spent two years and learned the techniques of the new discipline of bacteriology. He returned to New York and promptly became one of America’s preeminent bacteriologists. He established the first American course in that science. His reputation grew, and he was recruited to Johns Hopkins in 1885 as chairman of the department of pathology. From that post, he went on to become dean of the medical school and then acting president of the university. But he did not forget bacteriology, and he kept in his mind the idea of a separate institute or school that would contribute knowledge to the understanding of infectious diseases and the health problems related to them. He remembered the institutes of hygiene that had emerged in Germany and at which he had studied.