Prospects for measles immunization with reference to the relationship between distemper and measles viruses

The results of several cross-immunologic experiments in various animal species and in tissue culture failed to confirm the relationship between measles and distemper viruses that has been reported by others, dimming the hope that distemper virus might be used as an effective prophylactic against measles. In contrast, vaccination of children with attenuated measles virus promptly induced measles antibodies, even when the concentration of virus administered was only 6 TCD 50. In most instances, vaccination evoked mild clinical symptoms similar to those in gamma globulin-modified measles, the most prominent of these being fever that ranged from 38° to 40° C. and lasted one or two days. Rash also was recorded in a number of children, but Koplik spots and catarrhal signs were unusual. Affected children did not appear to be toxic or acutely ill; this was the case even in those who had significantly elevated temperatures. No virus was recovered, either from nasopharyngeal swabs taken on the seventh, ninth, and eleventh days after vaccination or from third-day blood samples, and no cases of secondary measles occurred in either institutionalized children or those living with their families. Questions about the vaccine still to be answered concern the duration of the immunity provided, the possibility of postvaccination encephalitis, and the ability of vaccinees to transmit the infection. Answers depend on the gradual and careful extension of trials in susceptible children.