Antibody level after measles vaccination

The present study was designed to estimate the level of measles IgG antibody in infants early after vaccination and in preschool children to determine their immune status. Three groups were studied: Group I, unvaccinated infants, Group II, recently vaccinated infants and Group III vaccinated preschool children. Measles IgG antibody was measured using the ELISA technique. The study showed that 90% (18/20) of the unvaccinated Group I infants were seronegative and only 10% were seropositive for measles IgG antibody representing most probably persisting maternal antibodies. Fifty percent (15/30) of recently vaccinated Group II infants were seropositive. A statistically significant higher antibody level was observed in Group II infants in comparison to those of Group I. The majority of seropositive infants of Group II (10/15 = 66.7%) showed high antibody level representing successful vaccination. Seropositives represented 77.4% (24/31) of Group III preschool children and the majority of them 75% (18/24) showed high antibody level which was significantly higher than the comparable in Group II infants, most probably due to subclinical infection in addition to successful vaccination. Fifty percent (15/30) of Group II infants and 22.6% (7/31) of Group III children were seronegative, more likely due to failure of initial vaccination.