title: Modeling the spread of polio in an IPV-vaccinated population: lessons learned from the 2013 silent outbreak in southern Israel.
abstract: Polio eradication is an extraordinary globally coordinated health program in terms of its magnitude and reach, leading to the elimination of wild poliovirus (WPV) in most parts of the world. In 2013, a silent outbreak of WPV was detected in Israel, a country using an inactivated polio vaccine (IPV) exclusively since 2005. The outbreak was detected using environmental surveillance (ES) of sewage reservoirs. Stool surveys indicated the outbreak to be restricted mainly to children under the age of 10 in the Bedouin population of southern Israel. In order to curtail the outbreak, a nationwide vaccination campaign using oral polio vaccine (OPV) was conducted, targeting all children under 10.
  
  
  
  A transmission model, fitted to the results of the stool surveys, with additional conditions set by the ES measurements, was used to evaluate the prevalence of WPV in Bedouin children and the effectiveness of the vaccination campaign. Employing the parameter estimates of the model fitting, the model was used to investigate the effect of alternative timings, coverages and dosages of the OPV campaign on the outcome of the outbreak.
  
  
  
  The mean estimate for the mean reproductive number was 1.77 (95 % credible interval, 1.46-2.30). With seasonal variation, the reproductive number maximum range was between zero and six. The mean estimate for the mean infectious periods was 16.8 (8.6-24.9) days. The modeling indicates the OPV campaign was effective in curtailing the outbreak. The mean estimate for the attack rate in Bedouin children under 10 at the end of 2014 was 42 % (22-65 %), whereas without the campaign the mean projected attack rate was 57 % (35-74 %). The campaign also likely shortened the duration of the outbreak by a mean estimate of 309 (2-846) days. A faster initiation of the OPV campaign could have reduced the incidence of WPV even if a lower coverage was reached, at the risk of prolonging the outbreak.
  
  
  
  OPV campaigns are essential for interrupting WPV transmission, even in a developed country setting with a high coverage of IPV. In this setting, establishing ES of WPV circulation is particularly crucial for early detection and containment of an outbreak.
authors.affiliation: Bio-statistical Unit, The Gertner Institute for Epidemiology and Health Policy Research, Chaim Sheba Medical Center, Tel Hashomer, 52621, Israel. ramiyaari@gmail.com.|Biomathematics Unit, Department of Zoology, Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel. ramiyaari@gmail.com.
authors.forename: Rami
authors.initials: R
authors.lastname: Yaari
authors.affiliation: Public Health Services, Ministry of Health, Jerusalem, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Kaliner
authors.affiliation: Public Health Services, Ministry of Health, Jerusalem, Israel.|Faculty for Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Itamar
authors.initials: I
authors.lastname: Grotto
authors.affiliation: Department of Mathematics, ORT Braude College, Karmiel, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Katriel
authors.affiliation: Public Health Services, Ministry of Health, Jerusalem, Israel.|Faculty for Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Jacob
authors.initials: J
authors.lastname: Moran-Gilad
authors.affiliation: Central Virology Laboratory, Ministry of Health, Chaim Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: Danit
authors.initials: D
authors.lastname: Sofer
authors.affiliation: Central Virology Laboratory, Ministry of Health, Chaim Sheba Medical Center, Tel Hashomer, Israel.|School of Public Health, the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ella
authors.initials: E
authors.lastname: Mendelson
authors.affiliation: School of Public Health, the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.|Public Health England Immunisation, Hepatitis and Blood Safety Department, 61, Colindale Avenue, London, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miller
authors.affiliation: Bio-statistical Unit, The Gertner Institute for Epidemiology and Health Policy Research, Chaim Sheba Medical Center, Tel Hashomer, 52621, Israel.|School of Public Health, the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Amit
authors.initials: A
authors.lastname: Huppert
authors.forename: E
authors.initials: E
authors.lastname: Anis
authors.forename: E
authors.initials: E
authors.lastname: Kopel
authors.forename: Y
authors.initials: Y
authors.lastname: Manor
authors.forename: O
authors.initials: O
authors.lastname: Mor
authors.forename: L
authors.initials: L
authors.lastname: Shulman
authors.forename: R
authors.initials: R
authors.lastname: Singer
authors.forename: M
authors.initials: M
authors.lastname: Weil
mesh_terms: D018912:Arabs / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control; D006801:Humans; D007223:Infant; D007557:Israel / Q000453:epidemiology; D015233:Models, Statistical; D011051:Poliomyelitis / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission*; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage*; D014611:Vaccination / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D011054:Poliovirus Vaccine, Inactivated; D011055:Poliovirus Vaccine, Oral
keywords: Inactivated polio vaccine; Model fitting; Oral polio vaccine; Polio; Transmission model; Vaccination strategies