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

Clin Microbiol Infect. 2022 Dec;28(12):1649.e1-1649.e8. doi: 10.1016/j.cmi.2022.07.004. Epub 2022 Jul 13.


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.

Keywords: ACWY; Adolescents; Conjugate vaccines; Herd immunity; Meningococcal Disease; Neisseria meningitidis; Pharyngeal carriage.

Publication types

  • Observational Study

MeSH terms

  • Adolescent
  • Cross-Sectional Studies
  • Humans
  • Meningococcal Infections* / epidemiology
  • Meningococcal Infections* / microbiology
  • Meningococcal Infections* / prevention & control
  • Meningococcal Vaccines*
  • Neisseria meningitidis* / genetics
  • United Kingdom / epidemiology
  • Vaccines, Conjugate


  • MenACWY
  • Vaccines, Conjugate
  • Meningococcal Vaccines