Evaluation of meningococcal serogroup C conjugate vaccine programs in Canadian children: Interim analysis

Background: To assess antibody titers afforded by meningococcal C- (MenC) tetanus toxoid conjugate vaccine at 12 months of age in three different immunization schedules. Methods: This prospective study included three similar cohorts of healthy infants from 1-dose, 2-dose and 3-dose MenC infant immunization programs. Infants were enrolled at 12 months of age and given the final scheduled dose of MenC-tetanus toxoid conjugate vaccine with sera collected prior to and 1 month after the vaccination. Serum bactericidal activity (SBA) titers >= 1:8 were considered protective. Results: Before the 12 month dose, participants had significantly different protective titers according to the number of prior doses received: 100% (95% Cl 97.6-100%) of infants who had 2 prior doses (at 2 and 4 months) were protected compared to 84.0% (76.7-89.3%) of participants with one dose (at 2 months) and 27.6% (21.0-35.4%) of unvaccinated infants. All subjects were protected after the 12 month MenC dose, but titers were higher with prior priming. Conclusions: Two MenC doses given in infancy afford optimal protection during the first year of life; however, substantial protection was seen after one dose at 2 months. (C) 2012 Elsevier Ltd. All rights reserved.