A Phase 2, Randomized, Control Trial of Group B Streptococcus (GBS) Type III Capsular Polysaccharide-tetanus Toxoid (GBS III-TT) Vaccine to Prevent Vaginal Colonization With GBS III.

Publication Type
Journal Article
Year of Publication
Hillier, Sharon L; Ferrieri, Patricia; Edwards, Morven S; Ewell, Marian; Ferris, Daron; Fine, Paul; Carey, Vincent; Meyn, Leslie; Hoagland, Dakota; Kasper, Dennis L; Paoletti, Lawrence C; Hill, Heather; Baker, Carol J
Clin Infect Dis
Date Published
2019 05 30
Adult; Antibodies, Bacterial; Bacterial Capsules; Female; Humans; Immunogenicity, Vaccine; Immunoglobulin G; Outcome Assessment, Health Care; Streptococcal Infections; Streptococcal Vaccines; Streptococcus agalactiae; Vaccination; Vaccines, Conjugate; Vaginosis, Bacterial; Young Adult

BACKGROUND: Group B Streptococcus (GBS) frequently colonizes pregnant women and can cause sepsis and meningitis in young infants. If colonization was prevented through maternal immunization, a reduction in perinatal GBS disease might be possible. A GBS type III capsular polysaccharide (CPS)-tetanus toxoid conjugate (III-TT) vaccine was evaluated for safety and efficacy in preventing acquisition of GBS colonization.

METHODS: Healthy, nonpregnant women aged 18-40 years and screened to be GBS III vaginal and rectal culture negative were randomized to receive III-TT conjugate or tetanus diphtheria toxoid vaccine in a multicenter, observer-blinded trial. GBS vaginal and rectal cultures and blood were obtained bimonthly over 18 months. Serum concentrations of GBS III CPS-specific antibodies were determined using enzyme-linked immunosorbent assay.

RESULTS: Among 1525 women screened, 650 were eligible for the intent-to-treat analysis. For time to first acquisition of vaginal GBS III, vaccine efficacy was 36% (95% confidence interval [CI], 1%-58%; P = .044), and for first rectal acquisition efficacy was 43% (95% CI, 11% to 63%; P = .014). Two months post-immunization, geometric mean concentrations of serum GBS type III CPS-specific immunoglobulin G were 12.6 µg/mL (95% CI, 9.95 to 15.81) in GBS III-TT recipients, representing a 4-fold increase from baseline in 95% of women, which persisted. Both vaccines were well tolerated.

CONCLUSIONS: GBS CPS III-TT conjugate vaccine significantly delayed acquisition of vaginal and rectal GBS III colonization. In addition to its use for maternal immunization to passively protect infants with maternally derived antibodies, a multivalent vaccine might also serve to reduce fetal and neonatal exposure to GBS.