Article ID: JJID.2020.411
The quadrivalent meningococcal polysaccharide diphtheria toxoid conjugate vaccine (Men-ACWY-D) is licensed in Japan since 2014. An earlier registration study demonstrated the immunogenicity of one dose in Japanese adults. Immunogenicity against serogroup C was lowest. Determination of the potential to increase the serogroup C response with a second dose was of interest. This study (NCT02591290) evaluated the safety and immunogenicity of two doses administered eight weeks apart to 60 healthy Japanese adults aged 20–55 years. Blood samples were collected 28–35 days after each vaccination. Immunogenicity endpoints included seroprotection and seroconversion rates. Safety assessments included systemic adverse events (AEs), non-serious AEs, and serious AEs. Fifty-eight (96.7%) participants completed the study. Seroprotection rates for serogroups A, C, W, and Y before vaccination were 76.8%, 26.8%, 26.8%, and 50.0%, increasing to 100%, 83.9%, 91.1%, and 96.4% and 100%, 92.9%, 94.6%, and 94.6%, respectively, after two doses. Seroconversion rates for the four serogroups were 100%, 93.8%, 97.1%, and 94.1% after the first dose and 100%, 96.9%, 100%, and 100% after the second. Increases between doses were insignificant. There were no safety concerns. The two-dose series is well tolerated but clinical benefit of a second dose within 8 weeks seemed to be low.
