Immunogenicity, Reactogenicity, and Safety of a Pentavalent Meningococcal ABCWY Vaccine in Adolescents and Young Adults who had Previously Received a Meningococcal ACWY Vaccine: Phase 3, Randomized, Controlled Clinical Study

Background: A MenABCWY vaccine containing 4CMenB and MenACWY-CRM vaccine components has been developed to protect against the five meningococcal serogroups that cause most invasive disease cases.

Methods: In this phase 3 study (NCT04707391), healthy participants aged 15-25 years, who had received MenACWY vaccination ≥4 years previously, were randomized (1:1) to receive two MenABCWY doses six months apart or one MenACWY-CRM dose. Primary objectives were to demonstrate the non-inferiority of MenABCWY 1 month post-vaccination versus MenACWY-CRM, with a lower limit of 2-sided 95% confidence interval above -10% for group differences in 4-fold rise in human serum bactericidal antibody (hSBA) titers against serogroups ACWY, and to evaluate reactogenicity and safety. Secondary endpoints included percentages of participants with hSBA titers ≥lower limit of quantitation (LLOQ) against serogroups ACWY and vaccine antigen-specific serogroup B (MenB) indicator strains.

Results: Non-inferiority of MenABCWY versus MenACWY-CRM was demonstrated following each MenABCWY dose. Percentages of participants with hSBA titers ≥LLOQ for serogroups ACWY were 97.9-98.9% and 99.5-100% following one and two MenABCWY doses, respectively, and 96.8-99.0% following one MenACWY-CRM dose. After two MenABCWY doses, 75.6-96.3% of participants had hSBA titers ≥LLOQ against MenB indicator strains. The MenABCWY vaccine was well tolerated in MenACWY-primed individuals with a favorable safety profile.

Conclusions: Immune responses against serogroups ACWY following one and two doses of investigational MenABCWY vaccine are non-inferior to those following MenACWY-CRM in MenACWY-primed adolescents and young adults. Robust immune responses were observed against MenB indicator strains after two MenABCWY doses administered 6 months apart.