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Coronavirus: Disease Control

Question for Department of Health and Social Care

UIN HL5431, tabled on 8 June 2020

To ask Her Majesty's Government what formal statistical confidence limit is represented by the very likely upper and lower bounds on the estimated COVID-19 reproduction rate, R, as published on the government website.

Answered on

9 July 2020

R is an average value that can vary in different parts of the country and communities. It cannot be measured directly, and calculating R becomes more uncertain when using small numbers of cases, either due to lower infection rates or smaller geographical areas.

Even when the overall United Kingdom R estimate is below 1, some regions may have R estimates that include ranges that exceed 1, for example from 0.7 to 1.1. This does not necessarily mean the epidemic regionally is increasing, just that the uncertainty in the data means it cannot be ruled out.

Estimates of R for geographies smaller than regional level are less reliable and it is more appropriate to identify local hotspots through, for example, monitoring numbers of cases, hospitalisations, and deaths.