Placental and breast transfer of antibodies after maternal immunization with polysaccharide meningococcal vaccine: a randomized, controlled evaluation.

We evaluated the strategy of maternal immunization with Neisseria meningitidis (Nm) vaccine in Asian mothers, to assess potential protection of infants, including by breast milk. One hundred and fifty-seven women in the third trimester were randomized to receive a single dose of the polysaccharide Nm (n=75) or a control vaccine (n=82). Group A Nm IgG levels were measured in maternal and infant sera, and specific IgA in breast milk. A 5.6-fold rise of Nm IgG antibody was observed among the Nm vaccinees. At delivery, geometric mean titres (GMTs) of Nm IgG antibody in Nm mothers was 12.5 microg/ml versus 4.97 microg/ml, with a mean infant/maternal antibody ratio of 0.56. Infants of Nm vaccinees had mean IgG levels of 6.9, 2.3, 1.2 and 0.6 microg/ml at 0, 6, 14 and 22 weeks, significantly higher than in control children up to 14 weeks. Anti-Nm IgA levels in milk were 6.8 to 2.0 microg/ml, significantly higher in Nm vaccinees till 6 months. Immunization during pregnancy is safe for both mothers and infants, and provides infants with significantly increased levels of specific IgG for 2-3 months and oral IgA for 6 months.