Optimal age for measles vaccination.

: Children in the age groups of 6-9 (group I) and >9-12 months (group II, control) 75 in each group, sex-matched were studied for antimeasles antibodies IgG and IgM by ELISA technique, before immunisation with Schwarz strain of measles vaccine. IgG antibodies were found in 66% in group I and none in group II, indicating the waning of maternal antibodies at an early age which come down before 6 months of age. After administration of measles vaccine to both the groups seroconversion was estimated at intervals of 4 weeks and 6 months after vaccination. Antimeasles IgM antibodies increased after vaccination and decreased 6 months after vaccination in both groups. Antimeasles IgG antibodies showed a significant increase in both groups. Increase was high in group II. This shows that anti-IgG antibodies to measles increased with age. The study shows the disappearance of protective level of immunisation at an early age. Seroconversion following vaccination at the age of 6 months is low, and hence a booster dose is recommended at 15 months.