 The study assessed the immunogenicity and safety of Sanofi Pasteur's investigational quadrivalent, serogroups A, C, Y, and W, meningococcal tetanostarxoid conjugate vaccine, MEN-ACYWTT, as a single dose in healthy meningococcal vaccine naive toddlers versus a licensed conjugate vaccine MCV4TT. The study found that the day 30 HSBA seroresponses were comparable between participants receiving MEN-ACYWTT and MCV4TT for each serogroup, with most unsolicited AES being of grade 1 or grade 2 intensity. If confirmed in phase 3, a single dose of the MEN-ACYWTT vaccine may show promise as an alternative vaccine option for toddlers receiving meningococcal vaccination for the first time. This article was authored by Timo Vesikari, Ray Boro, Ano Force 10, and others.