familial respiratory disease. Sixty-one children (22 families) less than 9 years of age and with negative histories for measles made up the basic study group. Alternate children received either vaccine or placebo, but within any one family there was always at least one child in each category. Both materials contained alum, and the immunization schedule consisted of 3 doses of 0.5 ml. of vaccine at intervals of 1 month. The unexpected occurrence of an epidemic of measles in the community interrupted this somewhat, in that the schedule was discontinued after exposure to the natural disease. A single lot of vaccine was used throughout.
This particular preparation produced serological conversion in 4% after 1 dose, 53% after 2, and 72% after 3 doses. A later lot, which is being used in a current investigation, seems to produce nearly 100% serological conversions, at least after 3 doses. Serum samples were obtained initially,