Safety and immunogenicity of a CRM or TT conjugated meningococcal vaccine in healthy toddlers

Background MenACWY-CRM (Menveo^®; GlaxoSmithKline) and MenACWY-TT (Nimenrix^®; Pfizer) are two meningococcal vaccines licensed in the European Union for use in both children and adults. While both vaccines target meningococcal serogroups A, C, W and Y, immunogenicity and reactogenicity of these quadrivalent meningococcal conjugate vaccines may differ due to differences in formulation processes and chemical structure. Yet data on the comparability of these two vaccines are limited. Methods The reactogenicity and immunogenicity of one dose of either MenACWY-CRM or MenACWY-TT were evaluated in healthy toddlers aged 12–15 months. Immunogenicity was assessed using serum bactericidal antibody assays (SBA) with human (hSBA) and rabbit (rSBA) complement. Results A total of 202 children aged 12–15 months were enrolled to receive one dose of MenACWY-CRM or MenACWY-TT. Similar numbers of subjects reported solicited reactions within 7 days following either vaccination. Tenderness at the injection site was the most common local reaction. Systemic reactions reported were similar for both vaccines and mostly mild to moderate in severity: irritability, sleepiness and change in eating habits were most commonly reported. Immunogenicity at 1 month post-vaccination was generally comparable for both vaccines across serogroups. At 6 months post-vaccination antibody persistence against serogroups C, W, and Y was substantial for both vaccines, as measured by both assay methodologies. For serogroup A, hSBA titers declined in both groups, while rSBA titers remained high. Conclusion Despite differences in composition, the MenACWY-CRM and MenACWY-TT vaccines have comparable reactogenicity and immunogenicity profiles. Immediate immune responses and short-term antibody persistence were largely similar between groups. Both vaccines were well-tolerated and no safety concerns were identified.