| Abstract: | Measles hemagglutination inhibition (HI) antibody titers of less than 1:4 were significantly (P less than 0.05) more prevalent among subjects born from 1962 through 1971 and vaccinated with a single dose of live measles virus vaccine at 12 months of age (14.5%) than among subjects born during the same years but vaccinated at 13 months or older (2.3%). For subjects born in 1972 through 1976, however, this difference was not statistically significant; titers of less than 1:4 occurred in 6.2% of those vaccinated at 12 months, compared to 0% in those vaccinated at 13 months or older. A decline in maternally derived measles HI antibody may be related to the increased rate of HI antibody titers of 1:4 or greater following vaccination of more recently born subjects. Following revaccination of subjects whose measles HI antibody titers were less than 1:4, measles HI titers were lower than would be expected after successful primary vaccination. Nevertheless, measles HI antibody persisted at a level of 1:4 or more until the latest titer measurement of this study (one to two years after revaccination) in 87.5% of those whose initial vaccination had been at 11 or 12 months of age. No adverse reactions to revaccination occurred. Revaccination programs should be considered for adolescents and young adults born before 1972 who received live measles virus vaccine at or before 12 months. Children born from 1972 through 1976 who were vaccinated at 12 months or later are not in need of revaccination. |
