An account has been given of 61 cases of naturally occurring classical typhus fever in patients who had received, previous to the onset of illness, one or more injections of Cox-type vaccine. The course of the disease in the vaccinated has been contrasted with the course in 54 unvaccinated patients.
It is concluded that two or more doses of Cox-type vaccine (1 cc. each) given 3 weeks or more before the onset of typhus reduce the mortality as well as the severity of naturally acquired typhus fever as it occurs under the conditions which prevail during epidemics.
It is regarded as possible that administration of vaccine during the incubation period of typhus will lessen the severity of illness. The authors recommend that vaccination be included in epidemic control programs.
Staff member, The Rockefeller Foundation, on leave.