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Table 1 Overview of key numerical assumptions of the models used

From: Characterization of outbreak response strategies and potential vaccine stockpile needs for the polio endgame

Assumption Value Sourcea
DEB model (Values based on expert review [12, 21, 22] and model calibration [9, 10] process)
Relative contribution to transmission compared to fully susceptible, by immunity stateb   [9, 17]
 Maternally immune 0.66;0.48
 1 successful IPV dose, recent 0.74;0.41
 1 successful IPV dose, last waning stage 0.90;0.36
 2 successful IPV doses, recent 0.42;0.06
 2 successful IPV doses, last waning stage 0.81;0.13
  ≥ 3 successful IPV doses, recent 0.28;0.04
  ≥ 3 successful IPV doses, last waning stage 0.72;0.06
 1 LPV infection, recent 0.07;0.05
 1 LPV infection, last waning stage 0.20;0.20
  ≥ 2 LPV infections or IPV and LPV (any # or order), recent 0.01;0.01
  ≥ 2 LPV infections of IPV and LPV (any # or order), lastwaning stage 0.08;0.06
Average time for maternally immune newborns to wane to fully susceptible [months] 3 [9]
Average time for other immunity states to wane from recent to fifth and last waning stage [years]   [9]
 Serotypes 1 and 2 4
 Serotype 3 3
Paralysis-to-infection ratio for WPVc   [9]
 Serotype 1 1/200
 Serotype 2 1/2000
 Serotype 3 1/1000
Relative R0 compared to serotype 1 R0   [9]
 Serotype 2 0.9
 Serotype 3 0.75
Relative R0 for OPV compared to homotypic WPV   [9, 10]
 Serotype 1 0.37
 Serotype 2 0.55
 Serotype 3 0.25
Average time to reach last of 20 reversion stages (i.e., fully-reverted VDPV, with same properties as homotypic WPV) [years]   [9, 10]
 Serotype 2 1.1
 Serotypes 1 and 3 1.7
Transmission threshold, i.e., minimal prevalence (weighed by contribution to transmission) for non-zero force-of-infection [effective infectious proportion] 5 per million [9]
Global model [2]
Timing of major events   
 bOPV introduction for some SIAs 2010
 IPV introduction (in populations using OPV-only in 2013) 2015
 tOPV intensification (until OPV2 cessation) 2015
 OPV2 cessation (in April) 2016
 OPV13 cessation (in April) 2019
 Last year when all populations use IPV 2024
 Last full year of analytical time horizon (Tend) 2052
Average per-dose take rate for OPVd [%]   [2, 24]
 tOPV, serotype 1 35–65
 tOPV, serotype 2 60–75
 tOPV, serotype 3 27–55
 mOPV, serotype 1 45–90  
 mOPV, serotype 2 60–95
 mOPV, serotype 3 45–85
 bOPV, serotype 1 42–80
 bOPV, serotype 3 42–80
Average per-dose take rates for IPV (any serotype)e [%]   [2]
 Low- and lower-middle income populations 63
 Upper middle-income populations 70
 High-income populations 75
Number of subpopulations with given R0 for WPV1f (N = 710)   [2, 7]
 4 20
 5 77
 6 43
 7 250
 8 90
 9 30
 10 30
 11 120
 12 20
 13 30
Number of subpopulations with given proportion of transmissions via oropharyngeal routeg (N = 710)   [2]
 0.3 290
 0.5 40
 0.6 233
 0.8 107
 0.9 40
RI coverage and schedules Variesh [2]
Preventive SIA impact and schedules Variesi [2, 5]
Cumulative effective infections needed to trigger a potential exportation from a subpopulation (exportation threshold) 200,000 [2]
iVDPV prevalence Variesj [7]
Average time between contacts of long-term iVDPV excretors with the general population [days] 150–600 [2]
Global rate of WPV and Sabin seed strain releases from randomly determined IPV production sites [per year] 1/5 [2]
Other poliovirus releases (i.e., inadvertent OPV use, unintentional release from laboratory, intentional release) Variesk [2]
  1. Abbreviations: bOPV bivalent oral poliovirus vaccine of serotypes 1 and 3, DEB model differential equation-based poliovirus transmission and OPV evolution model, IPV inactivated poliovirus vaccine, iVDPV immunodeficiency-associated vaccine-derived poliovirus, LPV live poliovirus, mOPV monovalent OPV, OPV oral poliovirus vaccine, OPV## cessation globally-coordinated cessation of OPV containing the serotype(s) indicated by ##, PID primary immunodeficiency disease, RI routine immunization, R 0 basic reproduction number, SIA supplemental immunization activity, T end end of the analytical time horizon (i.e., December 31, 2052), tOPV trivalent OPV, WPV(1,2,3) wild poliovirus (serotype 1, 2, or 3, respectively)
  2. aPublications that list the numerical assumption and/or provide methodological details
  3. bNumbers separate by semi-colons indicate contribution to a fecal-oral and oropharyngeal transmission, respectively
  4. cModel assumes half of these ratios for maternally immune individuals and full and permanent protection from paralysis in all other immunity states
  5. dValues vary by population and correlate with higher R0 values
  6. eIncludes priming response without seroconversion for first IPV dose
  7. fR0 values for OPV and VDPV/WPV of each serotype follow from relative R0 values in top section of table
  8. gLower values correlate with higher R0 values
  9. hSee source for values by subpopulation; technical details about characterization of RI provided in [9, 25]
  10. iSee sources for values by subpopulation; technical details about characterization of SIAs provided in [10]
  11. jGenerated by discrete-event simulation model of all global PID patients [7]
  12. kDepends on nature of release, income level, and time