The Phase III experiment looked at the quadrivalent meningococcal tetanus toxoid-conjugate vaccination as a booster. Individuals aged 15 years or older who have been immunised with a quadrivalent meningococcal conjugate vaccination (MCV4) or an approved MCV4. At baseline and 30 days after vaccination, functional antibodies against serogroups A, C, W, and Y were measured using a serum bactericidal antibody test with human complement. The proportions of individuals who achieved seroresponse were determined. Data on safety were obtained 180 days after immunisation.

Based on the proportion of individuals attaining hSBA vaccination seroresponse for each of the meningococcal serogroups at Day 30, MenACYW-TT indicated non-inferiority of the immunological response compared to MCV4-DT. Furthermore, at Day 30, 99 percent of individuals in both research groups exhibited hSBA titers 1:8 for the four meningococcal serogroups. The profiles of reactogenicity were comparable between groups. These Phase III findings in adolescents and adults demonstrate that MenACYW-TT increases immune response in people who have previously been primed with MCV4 vaccinations 4–10 years ago, regardless of whether MCV4-DT or MCV4-CRM was used for priming.