Persistence of the immune response at 5 years of age following infant immunisation with investigational quadrivalent MenACWY conjugate vaccine formulations

► Immune responses wane following infant MenACWY-CRM197 immunisation. ► Serogroup C immunity persists better after monovalent MenC conjugate priming. ► A MenACWY booster could provide broader protection against meningococcal disease. ► Further doses in later childhood are necessary for long-term immunity.