[Immunity against measles in mother-child binomials]

The persistence of passively adquired measles hemagglutination-inhibition (HI) antibody, was studied in a group of 50 mother-child binomials. In this longitudinal study, serial samples of blood were obtained from each infant during the first eight months of life. There was a high correlation between the level of the antibody titer in mothers and in their newborns. Passively antibody titers between 1:20 to 1:80, persisted as late as 8 months in more than 60% of infants. The presence of antibody may have a suppressive effect on the immunogenic response to live measles virus vaccine.