Transfer of measles, mumps, and rubella antibodies from mother to infant. Its effect on measles, mumps, and rubella immunization.

Sera from 42 mother-infant pairs were examined to determine the effect of passively acquired enhanced neutralizing (ENt) antibody on immunization. The ENt antibodies to measles, mumps, and rubella were greater in term newborns than in their mothers, with mean ratio of 1.8:1, 1.3:1, and 1.2:1, respectively. In 21% to 25% of the children, these antibodies persisted until 12 months of age. When immunized with trivalent measles-mumps-rubella vaccine, children who had persisting ENt measles and rubella titers had significantly lower mean antibody responses than children without detectable antibodies to the two viruses. Persisting ENt mumps antibodies did not affect the postimmunization titers. Seroconversion rates to any of the three viruses were not different in children with or without preexisting ENt antibody.