Maternal and infant antibody response to meningococcal vaccination in pregnancy.

The antigenic capacity of a mixed vaccine prepared with polysaccharides of meningococcus groups A and C, the placental transfer of antibodies, and the persistence of positive titres in the infant were evaluated in 21 pregnant women and their offspring during an epidemic of meningitis in São Paulo, Brazil; and antibody response was assessed in 29 infants vaccinated at less than 6 months of age. Antibodies were detected by passive haemagglutination; the high titres found and the high frequency of positive results are thought to be due to the use of a more sensitive technique. Increased antibody titres were found in most women, and there was evidence for passive transfer to the newborn, especially with regard to antibody type C. However, passive transfer was irregular, and the presence of antibodies in the mother did not guarantee their presence in the child. Passive transfer lasted for only 2-5 months. Vaccination in children under 6 months of age had poor results; only 1 child seroconverted.