Impact of the serogroup A meningococcal conjugate vaccine, MenAfriVac, on carriage and herd immunity

Clin Infect Dis. 2013 Feb;56(3):354-63. doi: 10.1093/cid/cis892. Epub 2012 Oct 19.


Background: The conjugate vaccine against serogroup A Neisseria meningitidis (NmA), MenAfriVac, was first introduced in mass vaccination campaigns of 1-29-year-olds in Burkina Faso in 2010. It is not known whether MenAfriVac has an impact on NmA carriage.

Methods: We conducted a repeated cross-sectional meningococcal carriage study in a representative portion of the 1-29-year-old population in 3 districts in Burkina Faso before and up to 13 months after vaccination. One district was vaccinated in September 2010, and the other 2 were vaccinated in December 2010. We analyzed 25 521 oropharyngeal samples, of which 22 093 were obtained after vaccination.

Results: In October-November 2010, NmA carriage prevalence in the unvaccinated districts was comparable to the baseline established in 2009, but absent in the vaccinated district. Serogroup X N. meningitidis (NmX) dominated in both vaccinated and unvaccinated districts. With 4 additional sampling campaigns performed throughout 2011 in the 3 districts, overall postvaccination meningococcal carriage prevalence was 6.95%, with NmX dominating but declining for each campaign (from 8.66% to 1.97%). Compared with a baseline NmA carriage prevalence of 0.39%, no NmA was identified after vaccination. Overall vaccination coverage in the population sampled was 89.7%, declining over time in 1-year-olds (from 87.1% to 26.5%), as unvaccinated infants reached 1 year of age. NmA carriage was eliminated in both the vaccinated and unvaccinated population from 3 weeks up to 13 months after mass vaccination (P = .003).

Conclusions: The disappearance of NmA carriage among both vaccinated and unvaccinated populations is consistent with a vaccine-induced herd immunity effect.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Burkina Faso
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Disease Outbreaks / prevention & control
  • Female
  • Humans
  • Immunity, Herd* / immunology
  • Infant
  • Male
  • Meningitis, Meningococcal / immunology
  • Meningitis, Meningococcal / microbiology
  • Meningitis, Meningococcal / prevention & control*
  • Meningococcal Vaccines / administration & dosage*
  • Neisseria meningitidis / immunology
  • Neisseria meningitidis / isolation & purification*
  • Prevalence
  • Vaccination
  • Young Adult


  • MenAfriVac
  • Meningococcal Vaccines