Group B Streptococcus Vaccine

A Group B streptococcus vaccine is a vaccine intended to prevent infection by Streptococcus agalactiae, the bacterium that causes Group B streptococcal disease, a serious and sometimes fatal infection especially dangerous to newborns, older adults and people with weakened immune systems; the most severe form, neonatal meningitis, is frequently lethal and can cause permanent neuro-cognitive impairment. Although national guidelines to screen pregnant women for Group B streptococcus carriage and the use of antibiotics during labor have significantly reduced early-onset disease in infants, they have not reduced late-onset disease in infants or infections in adults, and the World Health Organization has identified development of a maternal vaccine as a priority given the high unmet need; such a vaccine has been estimated to be able to prevent roughly 127,000 cases of early-onset disease, 87,000 cases of late-onset disease, 31,000 deaths and 18,000 cases of neuro-developmental impairment each year. As of 2026 no licensed vaccine exists, but as of winter 2023 two candidates were in clinical development: Pfizer's hexavalent GBS6, a polysaccharide-conjugate vaccine covering the six most prominent serotypes worldwide, then undergoing Phase 3 planning after promising Phase 2 immunogenicity results, and MinervaX's protein-based GBS-NN/NN2 vaccine, also undergoing preparations for Phase 3 after a completed Phase 1 adult trial.