Table 1.

Characteristics of outbreak response supplemental immunization activities (oSIAs) recommended prior to OPV2 cessation (21, 23) and currently in use after OPV2 cessation (27).

	Recommended oSIA (21, 23)	Current oSIA (27)
Vaccine choice and stockpile	mOPV2 stockpile designed for mOPV2 use up to 5 years post-OPV2 cessation, then anticipated shift to IPV	period of allowed mOPV2 use extended up to 8 years after OPV2 cessation (through 2023) (43), then extended indefinitely with anticipated use of nOPV2 (44, 45)
Scope	respond in all subpopulations in the blocks with R0 ≥ 10, otherwise just in outbreak subpopulation	respond in outbreak subpopulation and 4 worst-performing neighboring subpopulations within the same block when R0 ≥ 10, otherwise just in outbreak subpopulation
Days to first round	45 for first detection in block, 30 for other subpopulations in block	45 for first detection in block, 30 for other subpopulations in block
Size	4 rounds in blocks with R0 < 12, 6 rounds in blocks with R0 ≥ 12, all rounds 30 days apart	2 rounds separated by 30 days with 2 additional rounds after detection of breakthrough transmission
Intensity	true coverage 80%, repeatedly missed probability 70%	same as subpopulation-specific pSIAs, which ranges from true coverage 15%, repeatedly missed probability 95% to true coverage 80%, repeatedly missed probability 70% [see details in Kalkowska et al. (27)]
Target	greater of < 5 years old or all cohorts born since OPV cessation (whichever is larger)	< 5 years old