BACKGROUND: Invasive meningococcal disease, caused by Neisseria meningitidis, remains a significant health threat. This study examined the genetic diversity of serogroup B (NmB) organisms and assessed the potential coverage offered by the MenB-FHbp vaccine, licensed for individuals aged 10-25 years. NmB vaccines have not yet been incorporated into most routine immunization programs in Canada, with the exception of campaigns to deal with specific outbreaks and targeted vaccination efforts for at-risk groups.
METHODS: From 2013 to 2020, NmB strains causing invasive meningococcal disease were collected through the Canadian Immunization Monitoring Program ACTive surveillance network. Each isolate underwent analysis to determine clonal complex (CC) and factor-H binding protein peptide (fHbp), and fHbp surface expression using the Meningococcal Antigen Surface Expression (MEASURE) assay.
RESULTS: Of 119 isolates analyzed, 118 coded for full-length fHbp. CC-269 (48 isolates) and CC-41/44 (42 isolates) represented 75.6 % of all isolates. fHbp peptide 15 was the most prevalent peptide up until 2015 (47.4-53.9 %) but declined to 0-22.1 % afterwards. Median fHbp surface expression overall was 4270 MFI (IQR 2132-14,462). Peptides 15 and 210 (both CC-269) had the highest fHbp surface expression: peptide 15 (median: 18,446, IQR: 14,462-22,170) and peptide 210 (median: 28,306, IQR 24,935-31,678). Notably, 90.8 % of isolates had fHbp surface expression at a level associated with MenB-FHbp protection.
CONCLUSION: CC-269 and CC-41/44 predominated in 2013-2020. Notably, peptide 15, the most prevalent until 2015, declined significantly thereafter. The majority of isolates expressed fHbp at a level associated with vaccine-induced protection. A wider age authorization for the vaccine may result in increased prevention of NmB disease.