A Collaborative Study of Measles Vaccines in Five United States Communities

Abstract

Divided randomly into 4 treatment groups, 4798 school children have been given 3 injections of 0.5 ml of killed vaccine, or 2 injections of 0.5 ml of killed vaccine followed by an injection of live measles vaccine, or placebo injections. Conducted throughout as a double-blind study, surveillance for cases of measles is being maintained, and periodic blood samples for serology are being drawn on a random 10% of the participating children. Both measles vaccine schedules provided significant protection during the 4-month surveillance period following the 3rd injection. Contrasted to over 100 cases of measles occurring in each of the 2 placebo groups, those receiving killed vaccine had 20 cases of measles for a calculated effectiveness of 82%; those children receiving 2 injections of killed vaccine followed by one of live measles vaccine, experienced 3 cases of measles for an effectiveness of 97%. The distribution of the antibody levels evoked by the 2 vaccine schedules revealed significantly higher hemagglutination inhibition titers among those receiving the killed-live measles vaccine schedule.