CONTROLLED trials of a high passage rubella virus strain conducted by Meyer et al in institutionalized human subjects1 indicated that the virus was attenuated, immunogenic, and did not spread from vaccinees to others. The present investigation was undertaken to extend these observations in younger institutionalized subjects.
Description of Population and Plan of Study.—The study population was selected from a group of 45 severely retarded children, the majority of whom are less than 6 years of age, who reside in a small private institution near Cleveland. In February 1966, blood samples were obtained from all children in the institution as well as from the personnel caring for them. These were tested at the Division of Biologic Standards (DBS), National Institutes of Health, for rubellaneutralizing antibody according to techniques previously described.2 Thirty-two children were found to have an antibody titer of less than 1:2 to rubella virus. The other