Impact of meningococcal ACWY conjugate vaccines on pharyngeal carriage in adolescents: evidence for herd protection from the UK MenACWY programme.

Carr, JP; MacLennan, JM; Plested, E; Bratcher, HB; Harrison, OB; Aley, PK; Bray, JE; Camara, S; Rodrigues, CM

; Davis, K; +29 more...Bartolf, A; Baxter, D; Cameron, JC; Cunningham, R; Faust, SN; Fidler, K; Gowda, R; Heath, PT; Hughes, S; Khajuria, S; Orr, D; Raman, M; Smith, A; Turner, DP; Whittaker, E; Williams, CJ; Zipitis, CS; Pollard, AJ; Oliver, J; Morales-Aza, B; Lekshmi, A; Clark, SA; Borrow, R; Christensen, H; Trotter, C; Finn, A; Maiden, MC; Snape, MD; UKMenCar4 and ‘Be on the TEAM’ Study Collaborators and (2022) Impact of meningococcal ACWY conjugate vaccines on pharyngeal carriage in adolescents: evidence for herd protection from the UK MenACWY programme. Clinical Microbiology and Infection, 28 (12). 1649.e1-1649.e8. ISSN 1198-743X DOI: 10.1016/j.cmi.2022.07.004

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OBJECTIVE: Serogroup W and Y invasive meningococcal disease increased globally from 2000 onwards. Responding to a rapid increase in serogroup W clonal complex 11 (W:cc11) invasive meningococcal disease, the UK replaced an adolescent booster dose of meningococcal C conjugate vaccine with quadrivalent MenACWY conjugate vaccine in 2015. By 2018, the vaccine coverage in the eligible school cohorts aged 14 to 19 years was 84%. We assessed the impact of the MenACWY vaccination programme on meningococcal carriage. METHODS: An observational study of culture-defined oropharyngeal meningococcal carriage prevalence before and after the start of the MenACWY vaccination programme in UK school students, aged 15 to 19 years, using two cross-sectional studies: 2014 to 2015 "UKMenCar4" and 2018 "Be on the TEAM" (ISRCTN75858406). RESULTS: A total of 10 625 participants preimplementation and 13 438 postimplementation were included. Carriage of genogroups C, W, and Y (combined) decreased from 2.03 to 0.71% (OR 0.34 [95% CI 0.27-0.44], p < 0.001). Carriage of genogroup B meningococci did not change (1.26% vs 1.23% [95% CI 0.77-1.22], p = 0.80) and genogroup C remained rare (n = 7/10 625 vs 17/13 438, p = 0.135). The proportion of serogroup positive isolates (i.e. those expressing capsule) decreased for genogroup W by 53.8% (95% CI -5.0 - 79.8, p = 0.016) and for genogroup Y by 30.1% (95% CI 8.946·3, p = 0.0025). DISCUSSION: The UK MenACWY vaccination programme reduced carriage acquisition of genogroup and serogroup Y and W meningococci and sustained low levels of genogroup C carriage. These data support the use of quadrivalent MenACWY conjugate vaccine for indirect (herd) protection.