title: Modeling strategies to increase population immunity and prevent poliovirus transmission in the high-risk area of northwest Nigeria.
abstract: BACKGROUND
  Nigeria continues to struggle in its efforts to eliminate circulating live polioviruses using oral poliovirus vaccine (OPV).
  
  
  METHODS
  We modeled population immunity, and we estimated cases and the timing of transmission die-out for numerous policies that could accelerate the elimination of wild poliovirus type 1 (WPV1) and help Nigeria manage the risks of circulating vaccine-derived polioviruses (cVDPVs). We used a differential-equation based poliovirus transmission and OPV evolution model focused on northwest Nigeria to characterize the impact and trade-offs of potential vaccination strategies, including the introduction of inactivated poliovirus vaccine (IPV).
  
  
  RESULTS
  Northwest Nigeria appears close to reaching the threshold of population immunity it must exceed to stop WPV1 transmission if it continues immunizing previously under-vaccinated children. Avoiding type 2 cVDPVs (cVDPV2s) will depend on using sufficient amounts of trivalent OPV, which will also reduce the risks of cVDPV2s after coordinated cessation of type 2-containing OPV (OPV2). Using IPV during the OPV cessation period may increase population immunity, but it leads to a much lower impact on cVDPV risks than ensuring sufficient trivalent OPV use prior to OPV2 cessation.
  
  
  CONCLUSIONS
  Northwest Nigeria needs to intensify and sustain its immunization efforts to achieve and maintain higher levels of population immunity.
authors.affiliation: Kid Risk, Inc, Orlando, Florida Delft University of Technology, Delft, The Netherlands.
authors.forename: Dominika A
authors.initials: DA
authors.lastname: Kalkowska
authors.affiliation: Kid Risk, Inc, Orlando, Florida.
authors.forename: Radboud J
authors.initials: RJ
authors.lastname: Duintjer Tebbens
authors.affiliation: Kid Risk, Inc, Orlando, Florida.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Thompson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009549:Nigeria / Q000453:epidemiology; D011051:Poliomyelitis / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission*; D017955:Poliovirus / Q000302:isolation & purification*; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage* / Q000276:immunology*; D014611:Vaccination / Q000379:methods* / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D011055:Poliovirus Vaccine, Oral
keywords: IPV; OPV; eradication; polio; population immunity