Yale's Vaccine Pioneer

Dorothy Millicent Horstmann, M.D., is justly honored as a major figure in public health—internationally, nationally and locally.

She made major contributions to the development and implementation of several vaccines during her remarkable career. Perhaps her most notable accomplishments involved the polio virus, but her studies of rubella in New Haven schoolchildren were critical to authorization of that vaccine. She did all of this as the first woman to be awarded tenure and a professorship at Yale School of Medicine in the Departments of Pediatrics and Epidemiology (the precursor to the Yale School of Public Health) and was the first woman at Yale University to receive an endowed chair. Horstmann was the recipient of many additional honors including election to the National Academy of Sciences and presidency of the Infectious Diseases Society of America.

In the laboratory, as she evaluated the mechanism of polio virus pathogenesis, she made the surprising discovery that the virus could be present in the bloodstream by evaluating the blood of 111 suspected polio cases at Yale New Haven Hospital. She found the virus in the blood of only one individual, but it was very early in the disease. She extended this finding to monkeys and confirmed that the virus was in the blood at early stages and was excreted from the gastrointestinal tract in later stages. The realization that the virus was present in the blood was of profound importance: First, it showed that the virus could infect the brain through the bloodstream, not by traveling along nerves as had been assumed up to that time. Second, it demonstrated that a vaccine that generated antibodies in the blood could effectively combat the virus.

Horstmann was also instrumental in evaluating the oral, live, attenuated Sabin polio vaccine and the inactivated Salk vaccine in several Connecticut towns, a village in Arizona and in Costa Rica. She also evaluated the oral vaccine in Czechoslovakia, Poland, and, most significantly, Russia. She carried out the Russia study for the World Health Organization, which led to the vaccine’s eventual distribution in the United States. These studies were the culmination of an intense scientific debate between proponents of the oral attenuated Sabin vaccine (including Horstmann) and those who favored the inactivated injectable Salk vaccine. In fact, both vaccines are used depending on various circumstances and together they have led to the near eradication of polio.

Horstmann’s accomplishments did not end there. She made major contributions to the clinical epidemiology of the rubella, coxsackie and echo viruses. Her rubella studies, for example, demonstrated that vaccine immunization was superior to natural infection in generating long-term protection and led to the licensing of rubella vaccine in children in the United States in 1969.

Dorothy Horstmann was born in 1911 in Spokane, Washington. She graduated from the University of California at Berkeley in 1936 and the University of California at San Francisco Medical School in 1940. This was during the depths of the Depression, and she supported her tuition by giving piano lessons. She arrived at Yale in 1942 and joined the group of John Rodman Paul, who led the Yale Poliomyelitis Unit. With the exception of a few years as a visiting researcher at other institutions, she spent her entire career at Yale.

She could often be found in her office at 60 College St., hard at work, even after “retirement.” She was a role model and inspiration to junior colleagues as a scientist and as a woman who had made sacrifices and overcome many obstacles during a time that was not friendly to professional women. It took Yale 20 years to grant her tenure, even though she had long established herself as a world-famous scientist.

Horstmann was fiercely committed to attaining the highest standards and pushed junior faculty as well to succeed. The Friday Journal clubs are legendary for providing an exciting forum to swap ideas and debate issues in infectious disease epidemiology. She was also a citizen of the world, enjoying cultural pursuits, particularly the opera and the music of Mozart and travel to visit colleagues in far-off places. Her pioneering achievements as a scientist, woman and vaccine developer have been and continue to be an inspiration to those who are carrying out outstanding work, especially during COVID-19, at YSPH.

Dorothy Horstmann died in New Haven in 2001. Her legacy is profound and enduring. She motivated generations of scientists, including many young women who shared her love of knowledge and discovery and fierce determination to succeed. I was one of them.