Skip to main content


Table 2 Outbreak response choices considered

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

Outbreak response choice Base case Alternative(s) Iterations considered Outcomes of interest
Initial number of oSIAsa 4 (R0 < 12) 3, 4, 5, 6, or 7 1 selected iteration Behavior
6 (R0 ≥ 12)
oSIA impact levelb,c B A, B, or C 1 selected iteration Behavior
Interval between oSIAs (days)c 30 15 1 selected iteration Behavior
Mixed IPV/OPV use (ring) None mOPV (outbreak subpopulation);
IPV (other subpopulations in block)
Selected iterations Behavior, mOPV exportations, new iVDPV excretors, OPV restarts
Duration of mOPV use after homotypic OPV cessation (years) 5 3, 10, 20, or through Tend All affected Effective mOPV exportations; new iVDPV excretors; OPV restarts
Geographical scope (minimum R0 to trigger block-wide response) 10 8 or 13 All affected Effective mOPV exportations; new iVDPV excretors; OPV restarts
Response delay (days)d and detection thresholde Delay 45 and threshold variable (initial detection) or delay 30 and threshold 1 (oSIAs ongoing in block) Delay always 30, 45, or 50 and threshold always variable All affected Behavior; OPV restarts
Serotype 2 vaccine between OPV2 and OPV13 cessation Serotype 2 mOPV tOPV, IPV All affected +1 iteration without tOPV intensification Population immunity; number and size of outbreak; OPV restarts
Finite mOPV stockpile Unlimited stockpiles 100 million filled and 400 million bulk doses of each mOPV serotype All affected Behavior; OPV restarts
  1. Abbreviations: IPV inactivated poliovirus vaccine, iVDPV immunodeficiency-associated vaccine-derived poliovirus; mOPV, monovalent OPV, OPV## cessation, globally-coordinated cessation of OPV containing the serotype(s) indicated by ##, OPV oral poliovirus vaccine, oSIA outbreak response supplemental immunization activity, R 0 basic reproduction number, T end end of the analytical time horizon (i.e., December 31, 2052), tOPV trivalent OPV
  2. aConsidered jointly with oSIA impact level and interval between oSIAs
  3. bKey for SIA impact levels: A = true coverage of 0.5 and repeated missed probability if 0.8; B = true coverage of 0.8 and repeated missed probability if 0.7; C = true coverage of 0.95 and repeated missed probability if 0.5
  4. cConsidered jointly with initial number of oSIAs
  5. dTime between detection and first day of first oSIA
  6. eCumulative number of paralytic cases per 10 million people to trigger a detection