Dose–response to type V group B streptococcal polysaccharide–tetanus toxoid conjugate vaccine in healthy adults

A phase 1, dose-escalating trial was conducted in healthy adults to evaluate immunogenicity and reactogenicity of a type V group B streptococcal (GBS) capsular polysaccharide (CPS)–tetanus toxoid (TT) conjugate vaccine. Participants received one dose of unconjugated V CPS (37 μg), V–TT (2.4 μg CPS/1.1 μg TT), V–TT (9.6 μg CPS/4.3 μg TT) or V–TT (38.5 μg CPS/17.0 μg TT). Each vaccine and all doses of V–TT were well-tolerated. V CPS-specific antibodies reached a peak 4–8 weeks after immunization and were significantly higher through 52 weeks post-immunization in recipients of V–TT at each dose than in uncoupled CPS vaccinees. V–TT vaccine-induced antibodies promoted opsonophagocytic killing of type V GBS and avidity maturation of V CPS-specific IgG.