Abstract
During the large epidemic of serogroups A and C meningococcal disease in Brazil, we studied the immunologic response to meningococcal polysaccharide vaccine in infants born to women vaccinated during pregnancy. Radioimmunoassay serum levels against serogroups A and C polysaccharide were more than threefold higher in vaccinated than in unvaccinated women at delivery. Cord blood levels were also threefold or higher in infants whose mothers were vaccinated while pregnant compared to infants born of unvaccinated mothers. Within 3 mo, the infants' A and C serum antibody levels declined by approximately 80%. When vaccinated at about 6 mo of age, infants born of vaccinated mothers had antibody responses to A and C polysaccharide vaccines indistinguishable from those born of unvaccinated mothers. The response did not vary with the trimester of vaccination. We conclude that the vaccination of pregnant women with groups A and C meningococcal polysaccharide vaccine does not produce immune tolerance in the subsequently born infants.