To ask the Secretary of State for Health and Social Care, if he will publish (a) the algorithm or methodology that combines the five indicators to determine the covid-19 tier system for an area and (b) how that methodology incorporates (i) geographic and (ii) other contextual inputs.
This answer is the replacement for a previous holding answer.
12 January 2021
Decisions on which area goes into which tier are primarily based on five key epidemiological indicators as follows:
- case detection rates in all age groups;
- case detection rates in over-60 year olds;
- the rate at which cases are rising or falling;
- the positivity rate or the number of positive cases detected as a percentage of tests taken; and
- the pressure on the National Health Service, including current and projected occupancy.
Whilst each metric is important in its own right, the interplay between each indicator for a given area is equally important. As a result, hard numerical thresholds on each metric are not set. The indicators are designed to provide a full picture of what is happening with the virus in any area so that suitable action can be taken. The Government will maintain an approach that continues to allow our decisions to be driven by the data and expert judgement.