MenACYW-TT is a quadrivalent meningococcal conjugate vaccine under research for the prevention of invasive meningococcal disease (IMD) caused by serogroups A, C, W, and Y in people aged 6 weeks and above. MenACYW-TT was compared to a quadrivalent meningococcal polysaccharide vaccination (MPSV4) in this Phase II, randomised, open-label, multicenter, exploratory research in 301 healthy individuals aged 56 years in the United States. MenACYW-TT or MPSV4 were given to participants in a 2:1 ratio. At baseline and 30 days after vaccination, functional antibodies against meningococcal serogroups A, C, W, and Y were measured using serum bactericidal tests with human (hSBA) or baby rabbit (rSBA) complement. Data on safety were obtained up to 30 days after immunisation.

In all vaccination groups, the proportion of study subjects having hSBA titers 1:8 against serogroups A, C, W, and Y was higher by Day 30 compared to baseline. After MenACYW-TT vaccination, the percentage of persons with hSBA titers 1:8 were equal to those after MPSV4 vaccination for serogroups A and C, but much higher than after MPSV4 for serogroups W and Y. For all four serogroups, the proportions of individuals having rSBA titers of 1:8 were comparable between vaccination groups. Both vaccinations have comparable reactogenicity profiles. The majority of uninvited adverse events (AEs) were of Grade 1 or Grade 2 severity, with no severe AEs recorded. In individuals aged 56 years, the MenACYW-TT conjugate vaccination was well tolerated and immunogenic.