Studies on the Prevention of Mumps

Abstract

Summary Studies have been reported on the serological response of human beings to subcutaneous vaccination with inactivated mumps virus, as measured by complement fixation and hemagglutination inhibition tests. Emphasis has been placed upon the results obtained in individuals judged susceptible to mumps by negative histories and serological tests prior to vaccination. Maximal complement-fixing antibody response was obtained 2–3 weeks after vaccination. A single injection of vaccine resulted in antibody responses indistinguishable from those recorded after 2 injections 2 weeks apart. The frequency of response, as well as the height of titers attained, depended upon the amount of vaccine injected. Only with 4 ml of vaccine, representing approximately a 20-fold concentrate of virus from allantoic fluid, did all susceptible individuals show some antibody response. A correlation between the serum titers obtained by the complement-fixation test with the virus antigen, and by the hemagglutination-inhibition reaction, indicated that the two technics very likely measure different antibodies. Although, in general, a high titer by one test was matched by a high antibody level in the other, the ratios of hemagglutination-inhibition to complement-fixation titers varied over a range far greater than could be ascribed to the variations inherent in the technics. An epidemic of mumps occurred 9–12 months after vaccination. The incidence of infection among the controls (63 cases in 193 individuals) was almost twice that encountered in the immunized group (46 cases in 250 individuals). This result gained in significance when the antibody levels attained 4–5 weeks after vaccination were correlated to the incidence of mumps. The incidence was highest in those who failed to respond with measurable antibodies to vaccination, and decreased markedly with the increase in the antibody level attained after immunization. Although there were discrepancies between the clinical diagnosis and serological tests performed after the epidemic had subsided, the general interpretation is not altered by inclusion of the doubtful cases. No serologically confirmed case was noted in the 33 individuals who had reached a complement-fixing titer of 1:16 or greater after vaccination. The data indicate that transitory immunity may be induced by subcutaneous vaccination with inactivated mumps virus and that its duration appears to be related to the height of antibody levels attained.