Neisseria meningitidis can cause invasive meningococcal illness, which is especially dangerous in young children. Researchers compared the immunogenicity and safety of a single dose of Sanofi Pasteur’s experimental quadrivalent meningococcal tetanus-toxoid conjugate vaccine, MenACYW-TT, to a licenced conjugate vaccination, MCV4-TT, in healthy meningococcal vaccine-naive children. In this Phase II research, 188 toddlers aged 12–24 months were randomly assigned to either MenACYW-TT or MCV4-TT. Human complement (hSBA) and baby rabbit complement (rSBA) serum bactericidal antibody tests were used to detect antibodies against each serogroup before and 30 days after immunisation. For 30 days, participants were followed for immediate adverse events (AEs) and post-vaccination AEs. The study was completed by all 188 participants. For each serogroup, the Day 30 hSBA sero responses were comparable between subjects receiving MenACYW-TT and MCV4-TT. The majority of uninvited AEs were of Grade 1 or Grade 2 severity. There were no acute hypersensitivity responses, nor were there any AEs or significant AEs that necessitated the study’s termination. MenACYW-TT vaccination was well tolerated and immunogenic in this preliminary trial.

A single dose of the MenACYW-TT vaccine, if validated in Phase III, may show potential as an alternate vaccine option for children getting meningococcal immunisation for the first time.