Safety and immunogenicity of a single dose of a quadrivalent meningococcal conjugate vaccine (MenACYW–D): a multicenter, blind-observer, randomized, phase III clinical trial in the Republic of Korea

Summary Objectives To assess the safety and immunogenicity of a meningococcal polysaccharide diphtheria toxoid conjugate vaccine (MenACYW–D) in a Korean population. Methods This was a phase III, blind-observer, controlled study in which participants aged 11–55 years were randomized (2:1 ratio) to a single dose of MenACYW–D or tetanus/diphtheria/acellular pertussis (Tdap) vaccine. Outcomes included rates of seroconversion against all serogroups (≥4-fold increase in antibody titer from pre-vaccination), geometric mean titers (GMTs) at days 0 and 28 based on a serum bactericidal assay using baby rabbit complement, rates of seroprotection (titer ≥1:128) at day 28, and safety. Results A total of 300 participants were enrolled in the study (200 MenACYW–D and 100 Tdap). Seroconversion rates for serogroups A, C, Y, and W-135 were 77.8%, 88.3%, 74.6%, and 92.4%, respectively, for the MenACYW–D group and 9.3%, 8.1%, 12.2%, and 8.2%, respectively, for the Tdap group. The proportions of participants with pre-vaccination titers ≥1:128 were 57.3%, 12.6%, 51.5%, and 22.2% for serogroups A, C, Y, and W-135, respectively; post-vaccination rates were 98.5%, 89.4%, 96.0%, and 95.0% for the MenACYW–D group. A lower proportion of participants reported solicited reactions with MenACYW–D (46.2%) compared with Tdap (76.8%). Conclusion A single dose of MenACYW–D was well tolerated and elicited a robust immune response in Korean adolescents and adults.