Dr. Krugman: Since 1953 approximately 400 cases of infectious hepatitis with jaundice have been observed at the Willowbrook State School on Staten Island. The studies to be described were carried out in collaboration with Dr. Robert Ward and Dr. Joan Giles of our staff, Dr. A. Milton Jacobs of Willowbrook State School and Dr. Oscar Bodansky of Sloan-Kettering Institute. I should like to present a progress report of our investigations which have been concerned with the prevention and natural history of infectious hepatitis at Willowbrook. (A report of these studies has recently appeared in the New England Journal of Medicine (248:407, 1958) to which the reader may refer for further details.)
It had been previously reported by Stokes and associates that the administration of gamma-globulin was followed by not only a lower incidence of hepatitis but also a prolongation of the protective effect. Stokes postulated that "passive-active" immunity was responsible for this phenomenon. The epidemic of hepatitis at Willowbrook provided us with an opportunity to test this hypothesis.
Effect of Gamma-globulin on the Frequency of Infectious Hepatitis. Figure 1 illustrates the course of the outbreak at Willowbrook beginning in January, 1955. As can be seen, hepatitis continued to occur at a rate of about two to three cases per week. The cases, predominantly in children, occurred in 18 buildings in the institution. In June of 1956 gamma-globulin, 0.01 ml/lb, was administered to approximately a third of the inmates of each building. The control and inoculated groups were comparable as to age and time of admission to Willowbrook.