Persistence of antibodies for 42 months following vaccination of adolescents with a meningococcal serogroups A, C, W-135, and Y tetanus toxoid conjugate vaccine (MenACWY-TT)

Summary Objectives A primary dose of the European Union (EU)-licensed meningococcal A, C, W-135, and Y tetanus toxoid conjugate vaccine (MenACWY-TT) was immunogenic and well-tolerated in subjects aged 15–19 years. This study assessed antibody persistence at 3.5 years after vaccination with a MenACWY-TT or a tetravalent ACWY polysaccharide vaccine (MenPS, control). Methods In the original study, participants were randomized to receive a single dose of MenACWY-TT or MenPS. Serum bactericidal activity using rabbit serum as exogenous complement source was evaluated up to 42 months post-vaccination. Results At 42 months post-vaccination with MenACWY-TT ( n =19) or MenPS ( n =17), all subjects in each group had serum bactericidal activity titers ≥1:8 against all serogroups, except for two subjects in the MenPS group against serogroup C. Geometric mean antibody titers were higher than pre-vaccination levels at all post-vaccination time-points in both groups, and were significantly higher in the MenACWY-TT group versus the MenPS group for serogroup W-135 at month 42 (exploratory analysis). Conclusions These results indicate that seroprotection following primary vaccination with MenACWY-TT extends more than 3 years. Ongoing persistence data are required to understand the duration of protection following vaccination and to guide decisions on the need for future booster doses.