Dorothy M. Horstmann received her M.D. in 1940 from the University of California. She received additional training within the Vanderbilt Department of Medicine Staff for a year between 1941 and 1942. Horstmann then joined the Yale University Poliomyelitis Unit in 1943. Among her very notable achievements, Horstmann demonstrated that the polio virus reached the nervous system by way of the blood, a discovery that made polio vaccines possible. Later, she evaluated the oral vaccine program in Russia and studied the effectiveness of a rubella vaccine. In 1961, Horstmann became the first female full professor at the Yale School of Medicine. In 1969, the renowned epidemiologist, pediatrician, and virologist became the first woman at Yale to received an endowed chair, the John Rodman Paul Professor of Epidemiology.