LAUSR

BACKGROUND University students have high rates of pharyngeal carriage of Neisseria meningitidis. Interruption of carriage acquisition is an important mechanism of vaccines for inducing herd protection. 4CMenB and MenACWY-CRM vaccines have been shown to be immunogenic against meningococcal serogroups B and ACWY respectively in younger age groups, and also to elicit a modest impact on meningococcal carriage in vaccinated students. However, vaccine responses in university students and the impact of serum bactericidal antibody (SBA) titers on meningococcal carriage are undetermined. METHODS Immunogenicity of two 4CMenB doses or one MenACWY-CRM dose was measured in university students at Months 2, 4, 6 and 12 post-first vaccination. Immunogenicity of one MenACWY-CRM dose in students with previous meningococcal serogroup C conjugate vaccination was also assessed. Immune responses were measured with an SBA assay using human complement (hSBA) against three reference strains for serogroup B and against one strain for each for serogroups C and Y. Correlations between hSBA titers and meningococcal carriage were analyzed. RESULTS All subjects demonstrated robust functional antibody responses to both vaccines at Month 2 and a high proportion maintained protective hSBA titers up to Month 12. At baseline, carriage of disease-associated serogroup B strains and serogroups C and Y were higher in subjects with already-protective hSBA titers. Post-vaccination, while both 4CMenB and MenACWY-CRM elicited robust immunogenicity in students, significant correlations between post-vaccination hSBA titers and carriage of disease-associated serogroups were not observed. CONCLUSIONS 4CMenB and MenACWY-CRM were both highly immunogenic. There was no correlation between carriage and post-vaccination hSBA titers.