Immunogenicity of a Single Dose of Meningococcal Group C Conjugate Vaccine Given at 3 Months of Age to Healthy Infants in the United Kingdom

BACKGROUND:From 1999, in the United Kingdom, meningococcal C conjugate (MCC) vaccines from 3 manufacturers were introduced to the infant immunization schedule at 2, 3 and 4 months of age. In 2006, the schedule was refined to a 2-dose primary schedule at 3 and 4 months of age, with a combined MCC/Haemophilus influenzae type b (MCC/Hib-TT) booster at 12 months of age. Recent data have demonstrated that 2 of the 3 MCC vaccines showed potential for use as a single priming dose in infancy. METHODS:A randomized trial was undertaken with 2 MCC vaccines; one using tetanus toxoid carrier protein (MCC-TT) and one using CRM197 carrier protein (MCC-CRM197). Infants were immunized with MCC at 3 months of age followed by an MCC/Hib-TT booster at 12 months of age. RESULTS:The serum bactericidal antibody geometric mean titers 1 month after a single dose of MCC-TT or MCC-CRM 197 were 223.3 (95% confidence interval [CI]162.9–306.1) and 95.8 (95% CI66.4–138.2) with 100% and 95.5% of infants having serum bactericidal antibody titers ≥ 8, respectively. Before boosting, antibody titers had declined, and 1 month after the MCC/Hib-TT booster, serum bactericidal antibody geometric mean titers rose to 2251.0 (95% CI1535.3–3300.3) and 355.9 (95% CI235.4–538.1) for children primed with MCC-TT and MCC-CRM 197, respectively. CONCLUSIONS:In conclusion, a single priming dose of either MCC-TT or MCC-CRM197 administered at 3 months of age can be used together with the Hib/MCC-TT booster in the second year of life.