title: Combinations of Quality and Frequency of Immunization Activities to Stop and Prevent Poliovirus Transmission in the High-Risk Area of Northwest Nigeria.
abstract: BACKGROUND
  Frequent supplemental immunization activities (SIAs) with the oral poliovirus vaccine (OPV) represent the primary strategy to interrupt poliovirus transmission in the last endemic areas.
  
  
  METHODS
  Using a differential-equation based poliovirus transmission model tailored to high-risk areas in Nigeria, we perform one-way and multi-way sensitivity analyses to demonstrate the impact of different assumptions about routine immunization (RI) and the frequency and quality of SIAs on population immunity to transmission and persistence or emergence of circulating vaccine-derived polioviruses (cVDPVs) after OPV cessation.
  
  
  RESULTS
  More trivalent OPV use remains critical to avoid serotype 2 cVDPVs. RI schedules with or without inactivated polio vaccine (IPV) could significantly improve population immunity if coverage increases well above current levels in under-vaccinated subpopulations. Similarly, the impact of SIAs on overall population immunity and cVDPV risks depends on their ability to reach under-vaccinated groups (i.e., SIA quality). Lower SIA coverage in the under-vaccinated subpopulation results in a higher frequency of SIAs needed to maintain high enough population immunity to avoid cVDPVs after OPV cessation.
  
  
  CONCLUSIONS
  National immunization program managers in northwest Nigeria should recognize the benefits of increasing RI and SIA quality. Sufficiently improving RI coverage and improving SIA quality will reduce the frequency of SIAs required to stop and prevent future poliovirus transmission. Better information about the incremental costs to identify and reach under-vaccinated children would help determine the optimal balance between spending to increase SIA and RI quality and spending to increase SIA frequency.
authors.affiliation: Kid Risk, Inc., Orlando, Florida, United States of America.
authors.forename: Radboud J
authors.initials: RJ
authors.lastname: Duintjer Tebbens
authors.affiliation: Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Pallansch
authors.affiliation: Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Steven G F
authors.initials: SG
authors.lastname: Wassilak
authors.affiliation: Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Cochi
authors.affiliation: Kid Risk, Inc., Orlando, Florida, United States of America.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Thompson
mesh_terms: D002675:Child, Preschool; D060740:Disease Eradication; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data*; D007115:Immunization Schedule; D008962:Models, Theoretical; D009549:Nigeria / Q000453:epidemiology; D011051:Poliomyelitis / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission*; D017955:Poliovirus / Q000276:immunology*; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage / Q000276:immunology*; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D011055:Poliovirus Vaccine, Oral