The programme uses four distinct risk tiers to classify areas according to the risk they present and to devise risk appropriate eradication strategies and activities.

This includes core reservoir districts ( or Tier 1 districts), high-risk districts (or Tier 2 districts), vulnerable districts (or Tier 3 districts ), and low-risk districts (or Tier 4 districts).

A ‘core reservoir’ (Tier 1) refers to any clearly definable contiguous geographic zone spanning an area which has persistent local WPV1 circulation for at least 18 months and a repeated history of reseeding the virus outside immediate transmission zones.

Meanwhile, ‘high-risk districts’ (Tier 2) have detected intermittent transmission or sustained risk due to low levels of population immunity or other known risk factors.

Lastly, districts in Tiers 3 and 4 are determined based on variabilities in both quantitative and qualitative risk assessments

The tier classification of districts is shown on the map and table below:

Super High Risk Districts

In response to persistent virus transmission in a number of high-risk Union Councils (UCs), the programme has also developed strategies to prioritize those UCs which represent the greatest risk because they are comprised of dense, underserved population groups with poor levels of immunization against polio. These UCs are now categorized as Super-High Risk Union Councils or SHRUCs, and will receive ‘laser focus’ in terms of eradication interventions and strategies by the programme.

The National and Provincial Emergency Operations Centres (NEOC and PEOCs) have identified 40 SHRUCs within Tier 1 districts.

The provincial breakdown of SHRUCs is shown in the table below: