Abstract
BACKGROUND: Meningococcal serogroup B (MenB) strains are highly diverse. Breadth of immune response for the MenB vaccine, 4CMenB, administered at 0-2, 0-6, or 0-2-6 months, was demonstrated by endogenous complement-human serum bactericidal antibody (enc-hSBA) assay against an epidemiologically relevant panel of 110 MenB strains. METHODS: In a phase 3 trial, 3651 healthy 10- to 25-year-old participants were randomized 5:5:9:1 to receive 4CMenB (0-6 schedule), 4CMenB (0-2-6 schedule), investigational MenABCWY vaccine, or control MenACWY-CRM vaccine. The primary objectives were to evaluate safety and demonstrate breadth of immune response by enc-hSBA assay against the MenB strain panel using test-based (percentage of samples without bactericidal activity against strains after 4CMenB vs control vaccination) and responder-based (percentage of participants whose postvaccination sera kill ≥70% strains) approaches. Success was demonstrated with 2-sided 97.5% confidence interval (CI) lower limit >65%. Immunogenicity was assessed by traditional hSBA assay against four indicator strains. RESULTS: Breadth of immune response (test-based) was 78.7% (97.5% CI, 77.2-80.1), 81.8% (80.4-83.1), 83.2% (81.9-84.4) for the 0-2, 0-6, and 0-2-6 schedules, respectively, and (responder-based) 84.8% (81.8-87.5), 89.8% (87.2-92.0), and 93.4% (91.2-95.2), respectively. No clinically relevant differences in immunogenicity were observed across schedules. 4CMenB was well tolerated. CONCLUSIONS: The 2-dose (0-2, 0-6) 4CMenB schedules met predefined criteria for success for both breadth of immune response endpoints against a diverse MenB strain panel, had comparable immunogenicity, and safety in line with the established 4CMenB safety profile. The 3-dose schedule provided no additional immunological benefit, supporting use of the 4CMenB 0-2 schedule.