Antibody Persistence and Response to a Booster Dose of a Quadrivalent Conjugate Vaccine for Meningococcal Disease in Adolescents

In a previous randomized phase 2 study in adolescents, a CRM197 meningococcal conjugate vaccine against serogroups A, C, W-135 and Y (MenACWY-CRM) was well tolerated and immunogenic, compared with a plain polysaccharide vaccine (MenACWY-PS).This extension study assessed antibody persistence 5 years after primary vaccination with MenACWY-CRM (n = 50) or MenACWY-PS (n = 51), and the immunogenicity and reactogenicity of a dose of MenACWY-CRM given 5 years after primary vaccination; antibody response was also compared with vaccine-naive controls (n = 54). The primary endpoints were the percentage of subjects with titers ≥8 by serum bactericidal activity assay using human complement (hSBA) 5 years after primary vaccination and hSBA geometric mean titers 1 month after the MenACWY-CRM dose given in the current study.Five years after primary vaccination, over 70% of subjects who had received MenACWY-CRM were seropositive (hSBA titers ≥8) for serogroups C, W-135 and Y; for serogroups C and Y, the percentages of seropositive subjects were significantly higher in subjects previously vaccinated with MenACWY-CRM than in subjects previously vaccinated with MenACWY-PS. The MenACWY-CRM dose given 5 years postprimary vaccination elicited an anamnestic response across serogroups in those previously vaccinated with MenACWY-CRM. Responses in those previously vaccinated with MenACWY-PS were less robust but adequate and similar to that seen in the vaccine-naive group, both in magnitude and kinetics. MenACWY-CRM was well tolerated in all 3 groups.MenACWY-CRM provided a broad and persistent immune response in adolescents. A subsequent dose of MenACWY-CRM elicited an adequate antibody response, regardless of vaccine history.