Reactogenicity and immunogenicity of measles–rubella combined vaccine in school-entry-aged subjects with naturally acquired measles immunity

Background The reintroduction of measles–rubella combined (MR) vaccination to Japan raised concerns about adverse events as well as immunogenicity related to booster immunization in subjects with naturally acquired immunity to measles or rubella. Methods The time course of reactogenicity and antibody responses in recipients with pre-existing immunity to measles through natural infection was observed. Eighteen children aged 80–104 months received MR booster vaccination; 16 of them had had previous rubella vaccination. Results There were virtually no clinical reactions related to booster vaccination, and a highly significant antibody response to rubella antigen, whereas the antibody rise to measles was statistically significant but poor. Conclusions Vaccination of individuals already immune is not harmful. Booster immunization to rubella for Japanese children is vitally important.