Measles antibody levels in 3 to 9 months old infants.

Measles HI antibody titre was estimated in 248 infants aged 3 to 9 months. A total of 129 (52.02%) infants were seropositive (HI antibody titre more than 1:8). Geometric mean titre (GMT) and percentage of seropositive infants decreased with age and was minimum i.e., 5.52 and 22.22% respectively at the age of 7 months. After the age of 7 months the GMT and percentage of seropositive infants increased indicating that optimum age-of measles immunization in the area studied is around 7 months. Percentage of seropositivity did not differ significantly in relation to sex, socio-economic status and national status of infant.