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Coronavirus: Disease Control

Question for Department of Health and Social Care

UIN 96740, tabled on 4 January 2022

To ask the Secretary of State for Health and Social Care, if he will set out the range of assumptions of virus spread and severity of illness used in his covid-19 response planning.

Answered on

3 March 2022

The Scientific Advisory Group for Emergencies (SAGE) provides advice to the Government on its response to the COVID-19 epidemic. Its operational subgroup, Scientific Pandemic Influenza Group on Modelling (SPI-M-O), modelled potential scenarios for the Omicron variant using a range of assumptions on indicators. These include parameters such as the transmission advantage and intrinsic severity of the Omicron variant over the Delta variant. SPI-M-O modellers use contemporaneous academic studies when setting their assumptions.

Such modelling is regularly updated to reflect changes in assumptions as and when more detailed studies are released. Where there is uncertainty in a parameter value, sensitivity analysis is used to explore the range of impact and inform the Government’s response. Given the large number of assumptions made for the parameters that feed into the modelling, the latest underlying assumptions used by SPI-M-O academic groups is available at the following link:

The UK Health Security Agency (UKHSA) also informs the scientific advice presented to the Government. The UKHSA undertakes studies and risk assessments on selected emergent variants, assessing transmissibility, immune evasion, growth advantage and infections severity based on available data from the UKHSA and academic partners. Variants are selected for assessment on the basis of growth, and the number and type of genetic mutations present. Risk assessments are updated regularly until stable assessments are reached and are available at the following link:

Detailed analyses of the indicators are published in the Technical Briefings, which are available at the following link: