Antibody persistence and booster response 68 months after vaccination at 2-10 years of age with one dose of MenACWY-TT conjugate vaccine

Background: We evaluated antibody persistence up to 68 months (M) post-vaccination with a quadrivalent meningococcal serogroups A, C, W and Y tetanus toxoid conjugate vaccine (MenACWY-TT) or a licensed monovalent MenC conjugate vaccine (MenC-CRM₁₉₇) and subsequent booster responses to MenACWY-TT in healthy European children.

Methods: In the initial study (NCT00674583), healthy children, 2-10 years of age, were randomized to receive a single dose of either MenACWY-TT or MenC-CRM₁₉₇. In the follow-up study, we present the persistence at 32, 44, 56, and 68 M post-vaccination, overall and stratified by age (2-5 and 6-10 years), and the immunogenicity and safety of MenACWY-TT administered to all study participants at M68 post-primary vaccination.

Results: At M68, 33.3% (age group 2-5 years) and 47.1% (age group 6-10 years) of the children vaccinated with MenACWY-TT, and 50.0% (age group 2-5 years) and 75.9% (age group 6-10 years) vaccinated with MenC-CRM₁₉₇ retained titers ≥1:8 for MenC, as assessed by a serum bactericidal assay using rabbit complement (rSBA). In the MenACWY-TT recipients, the percentages of children retaining rSBA titers ≥1:8 for MenA, MenW, and MenY were 81.7%, 47.3% and 66.7% in age group 2-5 years and 91.8%, 58,8% and 76.5% in age group 6-10 years, respectively. The booster dose induced robust responses (100% for all serogroups) and was well-tolerated.

Conclusions: Antibody persistence (rSBA titers ≥ 1:8) for serogroups A, W and Y was observed in more than 50.0% of the children 68 M after receiving one dose of MenACWY-TT; for MenC, antibody persistence was observed in more than one third of MenACWY-TT and more than half of MenC-CRM₁₉₇ recipients. Vaccination with a booster dose of MenACWY-TT induced robust immune responses for all serogroups.