title: Estimating the extent of vaccine-derived poliovirus infection.
abstract: BACKGROUND
  Eight outbreaks of paralytic polio attributable to circulating vaccine-derived poliovirus (cVDPV) have highlighted the risks associated with oral poliovirus vaccine (OPV) use in areas of low vaccination coverage and poor hygiene. As the Polio Eradication Initiative enters its final stages, it is important to consider the extent to which these viruses spread under different conditions, so that appropriate strategies can be devised to prevent or respond to future cVDPV outbreaks.
  
  
  RESULTS
  This paper examines epidemiological (temporal, geographic, age, vaccine history, social group, ascertainment), and virological (type, genetic diversity, virulence) parameters in order to infer the numbers of individuals likely to have been infected in each of these cVDPV outbreaks, and in association with single acute flaccid paralysis (AFP) cases attributable to VDPVs. Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection.
  
  
  CONCLUSIONS
  Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings. These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans.
authors.affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, England. alison.wringe@lshtm.ac.uk
authors.forename: Alison
authors.initials: A
authors.lastname: Wringe
authors.forename: Paul E M
authors.initials: PE
authors.lastname: Fine
authors.forename: Roland W
authors.initials: RW
authors.lastname: Sutter
authors.forename: Olen M
authors.initials: OM
authors.lastname: Kew
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D004293:Dominican Republic / Q000453:epidemiology; D004534:Egypt / Q000453:epidemiology; D014644:Genetic Variation / Q000502:physiology; D006205:Haiti / Q000453:epidemiology; D006801:Humans; D007214:Indonesia / Q000453:epidemiology; D007223:Infant; D011051:Poliomyelitis / Q000453:epidemiology* / Q000209:etiology* / Q000276:immunology / Q000821:virology; D017955:Poliovirus / Q000235:genetics / Q000302:isolation & purification; D023321:Poliovirus Vaccines / Q000009:adverse effects* / Q000235:genetics / Q000276:immunology; D011159:Population Surveillance; D012923:Social Class
chemical_list: D023321:Poliovirus Vaccines