Over 25% of the UK is likely to have had coronavirus already, a new study suggests.
Researchers from the University of Manchester have used local authority data to to calculate the R-value - the number of people infected by one person with COVID-19 - within each local authority area.
The data, from the 144 local authorities analysed, now gives an R value of well below 1.
Dr Adrian Heald, one of the researchers on the study, said: “COVID-19 is a highly infectious condition and very dangerous for a small group of people. However a much larger group seem to have low or no symptoms and have been unreported.
“This study tries to provide an estimate of the number of historic infections – and gives us all a glimmer of hope that there may be light at the end of the tunnel.
“We show how effective Social Distancing and Lockdown has been. Though this is a tragedy, it could have been far worse”.
By extrapolating the variation in infection rate between local authorities, the researchers suggest that over 25% of the UK could already have the virus.
Mike Stedman from Res Consortium who carried out the data analysis, said: “Using our experience working with the NHS on improving patient services, we conducted this work in our own time as we felt we could make a valuable contribution to the public and policy makers by calculating the progression in the local and national daily infection rate.
“The figures are not perfect, with the numbers of severely ill patients as a proportion of the total cases being used as a market for estimates of wider infection.
“Only extensive antibody testing could give us a more accurate picture - but as that is only just becoming available, we believe this form of modelling is important in informing the best approach to unlocking the population.”
Based on the findings, the researchers suggest that the UK government should start gradually easing social distancing measures.
However, other experts have raised concerns about the validity of the findings.
Dr Adam Kucharski, Associate Professor in Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said: “In the absence of direct measurements, models can be useful for estimating the extent of infection from wider data sources.
"However, given how difficult it is to estimate the extent of unreported cases in a population from reported cases alone, it is likely that there is huge uncertainty in the estimates produced by the model used in this paper, and unfortunately this uncertainty is not reflected in the single value quoted in the paper and the press release."
