Table 2.
Probability of success (POS) estimates (expected total cases) for different time periods by type and scenario.
| Scenario and Time Period | POS (Expected Cases) for 2024–2027 | POS (Expected Cases) for 2028–2035 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | 1 | 2 | 3 | 1 | 2 | 3 | ||||||
| mOPV a | 0 | (1151) | 0 | (19,004) | 0.68 | (100) | 0 | (164,443) | 0 | (84,645) | 0.41 | (200) |
| nOPV best a,b | 0 | (932) | 0 | (6298) | 0.81 | (91) | 0 | (110,095) | 0 | (35,210) | 0.41 | (122) |
| nOPV worst a,b | 0 | (1372) | 0 | (26,760) | 0.74 | (97) | 0 | (143,605) | 0 | (93,487) | 0.41 | (69) |
| Best nOPV, baseline b | 0 | (5043) | 0 | (2558) | 0.28 | (120) | 0 | (45,571) | 0 | (7444) | 0.41 | (40) |
| Worst nOPV, baseline b | 0 | (5043) | 0 | (19,146) | 0 | (125) | 0 | (105,401) | 0 | (62,558) | 0.41 | (103) |
| Best nOPV, intensification b,c | 0.97 | (347) | 0 | (1661) | 0.96 | (96) | 0.92 | (1698) | 0 | (4797) | 0.98 | (18) |
| Worst nOPV, intensification b,c | 0.78 | (382) | 0 | (14,895) | 0.96 | (87) | 0.78 | (10,100) | 0 | (57,103) | 0.98 | (70) |
Abbreviations: mOPV, monovalent OPV; nOPV, novel OPV; OPV, oral poliovirus vaccine; POS, probability of successful OPV cessation by the date indicated; pSIA, preventive supplemental immunization activity; VAPP, vaccine-associated paralytic polio. a Results for the same time periods from prior bOPV cessation modeling that included assumed degradation of surveillance quality and resultant delayed outbreak response and did not include the use of tOPV in some countries where it occurred expanded age groups targeted in Yemen or any improvements in the quality of SIAs in the consequential geographies of DRC and Nigeria [48]. b Similar to prior modeling [48], we apply bounding scenarios of (i) nOPV best, which uses type-specific nOPV for outbreak response assuming the same effectiveness as type-specific mOPV, no reversion despite transmissibility, and no VAPP [59,78], and (ii) nOPV worst, which uses type-specific nOPV for outbreak response post-type-specific OPV cessation, assumes 90% of the effectiveness of mOPV and prior assumptions for reduced reversion [59], which we further reduced here by 10%, and VAPP occurring at a rate 10% lower than the VAPP rate of mOPV in vaccine recipients (see text). c Intensification refers to the addition of bOPV pSIAs prior to bOPV cessation in 2027 to some model subpopulations (see Figure 1 and text for discussion of the impacts of the planned rounds and the expected reductions of cases for types 1 and 2 relative to the baselines).