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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