Antibody Persistence 3 Years after Immunization of Adolescents with Quadrivalent Meningococcal Conjugate Vaccine

BackgroundA quadrivalent meningococcal conjugate vaccine (MCV-4) is recommended for United States teenagers. The duration of protective immunity is unknown. We investigated serum antibody persistence 3 years after vaccination of adolescents MethodsSerum samples from participants of a randomized trial who had received MCV-4 (n=52) or polysaccharide vaccine (MPSV-4; n=48) and from unvaccinated controls (n=60) were assayed for serogroups C, W-135, and Y anticapsular antibody concentrations by use of a radioantigen binding assay and for bactericidal activity (in a human complement assay) and passive protection against serogroup C bacteremia in an infant rat model ResultsA higher proportion of participants in the vaccine groups had protective bactericidal titers (⩾1:4), compared with that in the control group (for MCV-4 recipients vs. controls, P