Table 1.
Description of the WHO standard operating procedure (SOP) indicators, timelines, and outbreak measures for response to VDPV events and outbreaks — worldwide, 2016–2020.
| Term | Description1 | Recommended Time from Day 0 per SOPs |
|---|---|---|
| SOP Indicator | ||
| Notification to WHO headquarters (HQ) of first virus detection | Date of notification to WHO HQ of first virus detected, either from an AFP case, a positive environmental sample, or a positive contact of AFP case. | Not included in SOPs but measured in this study. |
| Day 0: Notification of circulating virus | Date of receipt of Polio Laboratory Network sequencing report by WHO HQ. Classification of circulating virus may follow detection of two or more related viruses in-country. | |
| Previously isolated VDPVs, classified as ambiguous or pending classification, may be reclassified as circulating (i.e., an outbreak) if another related poliovirus is detected indicating evidence of transmission. | ||
| Public Health Emergency (PHE) declaration2 | Date national government declares PHE in a non-endemic country. If outbreaks in-country remain open, additional PHE declarations are not needed for subsequent cVDPV2 outbreaks. |
3 days |
| Round 0 (R0) Start | Beginning of initial response of rapid, focused, and small-scale round; maximize quality in high-risk areas near detection. Conduct rapid (<14 days), focused response of 100,000–400,000 children. | 14 days |
| Round 1 (R1) Start | Beginning of increased response size (1–4 million children) in order to improve chance of rapidly stopping transmission. | 28 days |
| Round 2 (R2) End | Completion of increased response size (1–4 million children) in order to improve chance of rapidly stopping transmission. | 56 days |
| Time to stop an outbreak | Number of days to stop an outbreak per SOPs, i.e., date of last collection of a positive environmental sample or virus isolation or onset of paralysis from Day 0. | 120 days |
| Outcome measure | ||
| Breakthrough infection | Detection of AFP case, environmental isolate, or evidence of ongoing transmission 14 days or more after the completion of the second round of SIAs. | |
| Number of mOPV2 response rounds | Number of SIA rounds with mOPV2 use by December 31, 2021. Count includes rounds utilizing mOPV2 alone, mOPV2 in conjunction with IPV, or tOPV in Afghanistan and Pakistan. Excludes mop-ups. | |
| International spread | Emergence exported to other countries. | |
| Most recent isolation in country | Date of most recent cVDPV2 detection (by December 31, 2020). | |
| Outbreak closure | Date of outbreak closure announced by WHO Regional Office based on Outbreak Response Assessment (OBRA) recommendation. Requires quality surveillance and no detections of the poliovirus of the outbreak serotype for at least six months. |
Abbreviations: PHE, Public Health Emergency.
1According to Standard Operating Procedures for Responding to a Poliovirus Event or Outbreak (2020).
2PHE is declared for the first cVDPV2 outbreak in country.