Immune status following measles vaccination in infants and evaluation for the need of revaccination

In this prospective study, immune status of children vaccinated in infancy was determined at age 12-18 months. In 200 children, preimmunization protective measles hemagglutination (HI) antibody titres (greater than or equal to 1:8) were present in 38.5% of children of 6-8 months, the frequency decreased to 17.6 and 14.3% in age groups 9-11 and 12-18 months, respectively followed by an increasing incidence of 52.5% in those more than 18 months of age. Paired measles HI titre was estimated in 56 children, the post vaccination sample was taken at age 12-18 months, 3-9 months after measles vaccination. Most of the children (98.0%), with no detectable antibody titre, had a protective titre. Again a significant number (p less than 0.001) of children aged 12-18 months had protective HI titres compared to non-vaccinated. These findings suggest that when vaccinated at 9-11 months in our country, there is no need for revaccination later.