Immunization of pregnant women with group B streptococcal type III capsular polysaccharide-tetanus toxoid conjugate vaccine.

Objective: To determine the safety and immunogenicity of group B streptococcal (GBS) type III CPS-TT conjugate vaccine in pregnant women.

Methods: Prospective, randomized (2:1, vaccine:placebo), double-blind, placebo-controlled trial in women at 30-32 weeks' gestation and their infants. Immune responses were measured with IgG-specific ELISA assays; killing of III GBS by 1- and 2-month infant sera was assessed by opsonophagocytosis.

Results: Immunization was well-tolerated; maternal and infant outcomes were similar in vaccine and placebo groups. III-TT conjugate elicited good levels of IgG to III CPS that were functionally active against type III GBS through age 2 months.

Conclusions: Maternal immunization with GBS CPS-TT conjugates could prevent maternal, neonatal and young infant GBS disease.