Published 11 January 2021
In England, as many as 1 in 5 people, or 12.4 million, are estimated to have had the Covid-19 disease
The estimate is substantially higher than the 2.4 million confirmed cases from Public Health England, which is based on reported tests alone
The new modelling estimates the total number of cases in an area by comparing its number of deaths against an estimated infection fatality rate (IFR) – for more recent weeks data are based on extrapolations from reported case rates
The modelling shows substantial regional variations with over 50% of the population of Barking and Dagenham having had Covid-19 compared to less than 5% in Cornwall
New research suggests as many as 1 in 5 people, or 12.4 million, in England have had Covid-19. This is significantly higher than the 2.4 million reported cases from Public Health England (PHE). There is also substantial variation between local authorities (UTLAs) with 54.2% of Barking and Dagenham having had Covid-19 than 4.8% in Cornwall.
This reflects several difficult and challenging weeks where new infections have increased substantially. Up to the week of 7th of December 2020, an estimated 18% of people in England have had Covid-19 - up to 22% by the week commencing 28th of December 2020. The estimates are compatible with the most recent estimates of active infections in the community from the Office for National Statistics (ONS) Infection Survey[1,2]. The estimates model the population thought to have had Covid-19 since the beginning of the pandemic – they may differ slightly from antibody studies, as people who were infected with Covid-19 may lose antibodies over time.
Total cases are estimated by looking at each local authority’s (UTLA’s) Covid-19-related deaths as published by the ONS and their estimated infection fatality ratio (IFR).
The IFR is calculated by looking at a local authority’s age profile and applying age-specific infection fatality ratios from University of Cambridge research . These infection fatality rates are slightly lower for the second wave.
For more recent weeks, case numbers are estimated by extrapolating case numbers from PHE confirmed cases using the historical ratio of cases to PHE confirmed cases. Extrapolating cases in this way will be sensitive to changes in testing behaviour and capacity so should be interpreted with these caveats. Since cases are extrapolated at the local authority level, there are sometimes small sample sizes when calculating the ratio - for this reason, three months of testing data is used for estimating the rates.
George Batchelor, Cofounder and Director of Edge Health, said:
“Reported tests are only a fraction of the picture of total infections, which show how badly hit London and the north-west have been during the pandemic. It is incredible that the level of understanding of where and how infections are occurring is not greater at this stage, since it would allow control measures to be more targeted.