Background: The aim of this study was to evaluate antibody persistence 5 years after primary vaccination with the quadrivalent meningococcal conjugate vaccines MenACWY-CRM or MenACWY-D and 2 years after a booster dose of MenACWY-CRM, in the context of a phase 3 study.
Methods: Subjects (aged 19.2 ± 2.3 years) were assigned to 5 groups according to whether they had previously received primary vaccination (at 14.2 ± 2.2 years) with MenACWY-CRM (N = 131) or MenACWY-D (N = 76), a booster dose of MenACWY-CRM 3 years after primary vaccination with MenACWY-CRM (N = 44) or MenACWY-D (N = 31) or no vaccination (N = 107). The immunogenicity measures were percentages of subjects with serum bactericidal activity (hSBA) ≥ 1:8 for serogroups A, C, W and Y and hSBA geometric mean titers. Comparisons with age-matched, vaccine-naive subjects were performed.
Results: A majority of subjects vaccinated 5 years previously maintained hSBA ≥ 1:8 against serogroups C, W and Y in the MenACWY-CRM (59%-82%) and MenACWY-D groups (54%-73%); this was lower for serogroup A in both groups. There was a decline in antibody titers after primary vaccination, especially in the first 2 years postprimary vaccination, with steady concentrations during the next 3 years. Two years after MenACWY-CRM booster vaccination the percentages of subjects with hSBA ≥ 1:8 ranged from 77% to 100% across serogroups and geometric mean titers were 2.5- to 8-fold higher than prebooster values across serogroups.
Conclusions: Booster vaccination with MenACWY-CRM elicited a robust immune response during the 2-year follow-up period, irrespective of previous vaccination.