A STUDY OF MATERNALLY DERIVED MEASLES ANTIBODY IN INFANTS BORN TO NATURALLY INFECTED AND VACCINATED WOMEN

Maternal, cord and infant measles antibody levels were measured and co mpared in a group of 411 vaccinated mothers and 240 unvaccinated mothe rs, and their babies, between 1983 and 1991. Maternal and cord sera we re tested by haemagglutination inhibition and/or enzyme-linked immunos orbent assay, and plaque reduction neutralization tests were also used to test infant sera. Geometric mean titres were significantly higher in the unvaccinated than in the vaccinated mothers (P < 0.001). Infant s born to mothers with a history of measles had higher antibody levels at birth than infants of vaccinated mothers and, although the differe nce narrowed over time, continued to have higher levels up to 30 weeks of age. Between 5 and 7 months of age significantly more of the child ren of vaccinated mothers had plaque reduction neutralization antibody levels below that which would interfere with vaccination. As the boos ting effect of circulating natural measles disappears, earlier measles vaccination may need to be considered, perhaps as part of a two-dose policy.