WHO-supported comparative studies of attenuated live measles virus vaccines.

UNDER THE AUSPICES OF WHO A COMPARATIVE STUDY OF ATTENUATED LIVE MEASLES VACCINES WAS MADE BY TEAMS IN FIVE COUNTRIES: Canada, Czechoslovakia, Nigeria, Switzerland and Yugoslavia. The reactions and antibody responses to Enders' Edmonston B vaccine with or without gamma-globulin and to the Schwarz, Beckenham and Milovanović vaccine were measured. In each trial Enders' Edmonston B vaccine with gamma-globulin was used as a "standard" vaccine, and in each trial there was also an unvaccinated control group. There were altogether 1685 children in the study-1317 vaccinated and 368 controls.Each team placed the vaccines in a similar order as to the percentages of children with rash and pyrexia after vaccination. The percentages of children with rash and pyrexia after injection of the same vaccine were, however, found to vary greatly between trials. It was therefore impossible to give accurate figures for the percentage of children who would develop pyrexia after any one vaccine, but in general terms the proportion of children with fever of 39.4 degrees C (103 degrees F) or more may be expected to vary from 10% to 30% depending on the vaccine used. Six of the vaccinated children (0.5%) had convulsions 6-9 days after vaccination, but no other serious reactions and no permanent sequelae were recorded. No convulsions occurred in the unvaccinated control groups. The antibody responses were measured by the haemagglutination-inhibition test; nearly all children gave an antibody response but this varied with the vaccine employed. Children given vaccines causing the most reaction had the highest antibody levels.