title: Impact of the serogroup A meningococcal conjugate vaccine, MenAfriVac, on carriage and herd immunity.
abstract: 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.
authors.affiliation: Norwegian Institute of Public Health, University of Oslo, Norway. paul.kristiansen@fhi.no
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kristiansen
authors.forename: Fabien
authors.initials: F
authors.lastname: Diomandé
authors.forename: Absatou Ky
authors.initials: AK
authors.lastname: Ba
authors.forename: Idrissa
authors.initials: I
authors.lastname: Sanou
authors.forename: Abdoul-Salam
authors.initials: AS
authors.lastname: Ouédraogo
authors.forename: Rasmata
authors.initials: R
authors.lastname: Ouédraogo
authors.forename: Lassana
authors.initials: L
authors.lastname: Sangaré
authors.forename: Denis
authors.initials: D
authors.lastname: Kandolo
authors.forename: Flavien
authors.initials: F
authors.lastname: Aké
authors.forename: Inger Marie
authors.initials: IM
authors.lastname: Saga
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Clark
authors.forename: Lara
authors.initials: L
authors.lastname: Misegades
authors.forename: Stacey W
authors.initials: SW
authors.lastname: Martin
authors.forename: Jennifer Dolan
authors.initials: JD
authors.lastname: Thomas
authors.forename: Sylvestre R
authors.initials: SR
authors.lastname: Tiendrebeogo
authors.forename: Musa
authors.initials: M
authors.lastname: Hassan-King
authors.forename: Mamoudou H
authors.initials: MH
authors.lastname: Djingarey
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Messonnier
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Préziosi
authors.forename: F Marc
authors.initials: FM
authors.lastname: Laforce
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Caugant
mesh_terms: D000293:Adolescent; D000328:Adult; D002050:Burkina Faso; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks / Q000517:prevention & control; D005260:Female; D006801:Humans; D032521:Immunity, Herd / Q000276:immunology; D007223:Infant; D008297:Male; D008585:Meningitis, Meningococcal / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D009345:Neisseria meningitidis / Q000276:immunology / Q000302:isolation & purification*; D015995:Prevalence; D014611:Vaccination; D055815:Young Adult
chemical_list: C573970:MenAfriVac; D022401:Meningococcal Vaccines