Immune Responses to Booster Vaccination with Meningococcal ABCWY Vaccine Following Primary Vaccination with Either Investigational or Licensed Vaccines: A Phase 2 Randomized Study.

Background: Current meningococcal prime-boost vaccination schedules include separate vaccines for serogroups ACWY and B. An investigational combined serogroups ABCWY vaccine (MenAB-CWY) was developed to protect against clinically important Neisseria meningitidis serogroups. Methods: In this phase 2, randomized, observer-blind, extension study (NCT01272180), participants 10-25 years of age received 1 booster dose of MenABCWY vaccine at 24 months (M) postprimary series of MenABCWY (2 doses), 4CMenB (2 doses) or MenACWY-CRM vaccine (1 dose). Immune responses to booster dose (1M postbooster) and antibody persistence (24M, 36M postprimary series) were assessed using bactericidal assay with human complement (hSBA). Reactogenicity and safety were -evaluated. Results: One hundred ninety participants were vaccinated. At 1M after the MenABCWY booster dose, seroresponse rates against serogroups ACWY ranged between 85% and 96%, 73% and 100% and 83% and 95% for participants previously receiving MenABCWY, 4CMenB and MenACWYCRM, respectively. At 12M postbooster dose, >= 67% of participants across all groups had hSBA titers >= 8 for serogroups ACWY, except in 4CMenB-primed individuals for serogroup Y (45%). Across MenABCWY and 4CMenB-primed groups, hSBA titers >= 5 across serogroup B test strains were observed in 82%-100% and 29%-100% of participants at 1M and 12M postbooster, respectively. Geometric mean titers against serogroups ACWY increased from pre-to 1M postboosting with MenABCWY and persisted at 12M. The reactogenicity and safety profile of MenABCWY was similar to that of 4CMenB. Conclusions: MenABCWY may be suitable for prime-boost schedules against meningococcal disease, including regimens involving a primary series of either 4CMenB or MenACWY-CRM licensed vaccines.