Figure 1. Participants’ progression through the study. ACWY-TT group, group of children who received one dose of MenACWY-TT; Men-PS group, group of children who received one dose of the MenACWY polysaccharide vaccine; ATP, according to protocol; TVC, total vaccinated cohort; N, number of children; *Reasons for non-eligibility: suboptimal responder re-vaccinated with a monovalent meningococcal serogroup C vaccine (n = 41); suboptimal responder who did not come to the booster vaccination visit (n = 2); consent withdrawal (n = 1); and acute leukemia (n = 1)