title: Time is (still) of the essence: quantifying the impact of emergency meningitis vaccination response in Katsina State, Nigeria.
abstract: BACKGROUND
  In 2009, a large meningitis A epidemic affected a broad region of northern Nigeria and southern Niger, resulting in more than 75 000 cases and 4000 deaths. In collaboration with state and federal agencies, Médecins Sans Frontières (MSF) intervened with a large-scale vaccination campaign using polysaccharide vaccine. Here the authors analyze the impact (cases averted) of the vaccination response as a function of the timing and coverage achieved.
  
  
  METHODS
  Phenomenological epidemic models were fitted to replicate meningitis surveillance data from the Nigerian Ministry of Health/WHO surveillance system and from reinforced surveillance conducted by MSF in both vaccinated and unvaccinated areas using a dynamic, state-space framework to account for under-reporting of cases.
  
  
  RESULTS
  The overall impact of the vaccination campaigns (reduction in meningitis cases) in Katsina State, northern Nigeria, ranged from 4% to 12%. At the local level, vaccination reduced cases by as much as 50% when campaigns were conducted early in the epidemic.
  
  
  CONCLUSIONS
  Reactive vaccination with polysaccharide vaccine during meningitis outbreaks can significantly reduce the case burden when conducted early and comprehensively. Introduction of the conjugate MenAfriVac vaccine has reduced rates of disease caused by serogroup A Neisseria meningitidis in the region. Despite this, reactive campaigns with polysaccharide vaccine remain a necessary and important tool for meningitis outbreak response.
authors.affiliation: Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802 USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ferrari
authors.affiliation: Epicentre, Paris, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Fermon
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Nackers
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Augusto
authors.initials: A
authors.lastname: Llosa
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Magone
authors.affiliation: Médecins Sans Frontières, Paris, France Rebecca.grais@epicentre.msf.org.
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Grais
mesh_terms: D000293:Adolescent; D000328:Adult; D001428:Bacterial Vaccines; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D032541:Mass Vaccination / Q000458:organization & administration*; D008585:Meningitis, Meningococcal / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000627:therapeutic use*; D009549:Nigeria / Q000453:epidemiology; D011135:Polysaccharides, Bacterial / Q000276:immunology; D055815:Young Adult
chemical_list: D001428:Bacterial Vaccines; D022401:Meningococcal Vaccines; D011135:Polysaccharides, Bacterial
keywords: Meningitis surveillance; Neisseria meningitidis serogroup A; Nigeria; Polysaccharide vaccine; Vaccination outbreak response