title: Identifying optimal vaccination strategies for serogroup A Neisseria meningitidis conjugate vaccine in the African meningitis belt.
abstract: OBJECTIVE
  The optimal long-term vaccination strategies to provide population-level protection against serogroup A Neisseria meningitidis (MenA) are unknown. We developed an age-structured mathematical model of MenA transmission, colonization, and disease in the African meningitis belt, and used this model to explore the impact of various vaccination strategies.
  
  
  METHODS
  The model stratifies the simulated population into groups based on age, infection status, and MenA antibody levels. We defined the model parameters (such as birth and death rates, age-specific incidence rates, and age-specific duration of protection) using published data and maximum likelihood estimation. We assessed the validity of the model by comparing simulated incidence of invasive MenA and prevalence of MenA carriage to observed incidence and carriage data.
  
  
  RESULTS
  The model fit well to observed age- and season-specific prevalence of carriage (mean pseudo-R2 0.84) and incidence of invasive disease (mean R2 0.89). The model is able to reproduce the observed dynamics of MenA epidemics in the African meningitis belt, including seasonal increases in incidence, with large epidemics occurring every eight to twelve years. Following a mass vaccination campaign of all persons 1-29 years of age, the most effective modeled vaccination strategy is to conduct mass vaccination campaigns every 5 years for children 1-5 years of age. Less frequent campaigns covering broader age groups would also be effective, although somewhat less so. Introducing conjugate MenA vaccine into the EPI vaccination schedule at 9 months of age results in higher predicted incidence than periodic mass campaigns.
  
  
  CONCLUSIONS
  We have developed the first mathematical model of MenA in Africa to incorporate age structures and progressively waning protection over time. Our model accurately reproduces key features of MenA epidemiology in the African meningitis belt. This model can help policy makers consider vaccine program effectiveness when determining the feasibility and benefits of MenA vaccination strategies.
authors.affiliation: Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. startof@gmail.com
authors.forename: Sara
authors.initials: S
authors.lastname: Tartof
authors.forename: Amanda
authors.initials: A
authors.lastname: Cohn
authors.forename: Félix
authors.initials: F
authors.lastname: Tarbangdo
authors.forename: Mamoudou H
authors.initials: MH
authors.lastname: Djingarey
authors.forename: Nancy
authors.initials: N
authors.lastname: Messonnier
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Clark
authors.forename: Jean Ludovic
authors.initials: JL
authors.lastname: Kambou
authors.forename: Ryan
authors.initials: R
authors.lastname: Novak
authors.forename: Fabien V K
authors.initials: FV
authors.lastname: Diomandé
authors.forename: Isaïe
authors.initials: I
authors.lastname: Medah
authors.forename: Michael L
authors.initials: ML
authors.lastname: Jackson
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D005240:Feasibility Studies; D054884:Host-Pathogen Interactions / Q000276:immunology; D006801:Humans; D015994:Incidence; D007223:Infant; D032541:Mass Vaccination / Q000379:methods; D008585:Meningitis, Meningococcal / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D018448:Models, Immunological; D009345:Neisseria meningitidis / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D015203:Reproducibility of Results; D014611:Vaccination / Q000379:methods*; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology*; D055815:Young Adult
chemical_list: D022401:Meningococcal Vaccines; D018074:Vaccines, Conjugate