Tyler Harvey-Cowlishaw, Sophie Wartnaby, Jorge Trujillo-Mendoza, Jack L Clark, Aiswarya Lekshmi, Stephen A Clark, Simon Royal, Christopher D Bayliss, David P J Turner, Neil J Oldfield
Our study provides information on the meningococcal lineages and serogroups circulating in a key reservoir in the post-pandemic era. The absence of encapsulated genogroup W and Y isolates in this student cohort confirms that the UK's adolescent MenACWY vaccination program effectively protects young adults from serogroup W and Y carriage acquisition. The presence of genetically diverse genogroup B carriage isolates, including hyperinvasive lineages, supports consideration of strategies to further reduce IMD in at risk student populations.
BACKGROUND: Neisseria meningitidis is a commensal bacterium that asymptomatically colonizes the nasopharynx but can cause invasive meningococcal disease (IMD). Carriage studies are essential to complement disease surveillance and for evaluating the impact of vaccination programs. This study aimed to determine meningococcal carriage prevalence and distribution of lineages in UK university students, a key group at increased risk of carriage and IMD.
METHODS: We collected oropharyngeal swab samples from 400 new students at a UK university during Welcome Week (September 2024). Some participants were resampled in November 2024. Culture-amplified polymerase chain reaction (PCR) was applied to detect viable meningococci and determine capsule genogroups. Dot-blot ELISA established isolate capsule expression status (serogroup). Whole genome sequencing established genogroup/clonal complex combinations, population phylogenies, and predicted coverage by licensed group B vaccines.
RESULTS: The September meningococcal carriage rate was 12.5%, which rose significantly to 25.3% in November. The genogroups of recovered isolates were B (34.3%; of which 58.3% expressed capsule), capsule null (24.3%), E (21.4%), Y (12.9%), not genogroupable (5.7%) and W (1.4%). No genogroup C-positive carriers were identified. None of the isolates from genogroups Y or W expressed capsule. For genogroup Y, a statistically significant increase in prevalence was detected between time points (1 to 6.3%). For genogroup B, multiple different clonal complexes were represented, including hyper-invasive lineages responsible for a high proportion of UK IMD cases. The majority of recovered genogroup Y belonged to the β-lactamase-encoding, penicillin-resistant, ST-3587 lineage.
CONCLUSION: Our study provides information on the meningococcal lineages and serogroups circulating in a key reservoir in the post-pandemic era. The absence of encapsulated genogroup W and Y isolates in this student cohort confirms that the UK's adolescent MenACWY vaccination program effectively protects young adults from serogroup W and Y carriage acquisition. The presence of genetically diverse genogroup B carriage isolates, including hyperinvasive lineages, supports consideration of strategies to further reduce IMD in at risk student populations.