Up to four in 10 Covid infections in the first wave may have caught the virus in hospital, according to the latest research.
Those infections would have had a 'substantial' impact on deaths, government
papers show.
It was previously thought that the figure was around a fifth, or one in five.
But researchers at Public Health England and the London School of Hygiene and Tropical Medicine also looked at the numbers of people testing positive within two weeks of discharge.
Under the most conservative estimate, which only included people infected after at least 15 days in hospital, just 8.8 per cent of infections were found to be “nosocomial” or acquired in hospital, equating to 7,906 people, reports The Telegraph.
However, under the least conservative estimates, which included those testing positive within three days of entering hospital or 14 days after discharge, the figure rises to 40.5 per cent of hospital infections – a total of 36,152 people.
However the NHS national medical director Professor Stephen Powis said the root cause of hospital infections lay with rising cases in the community.
The Telegraph reports that separate modelling by the same group using different data from the Covid-19 Clinical Information Network concludes there may have been 31,070 hospital infections in England over the first wave.
Minutes from the Scientific Advisory Group for Emergencies (Sage) show that experts have been aware of the paper since October.
On Friday the Government Office for Science released an updated version of the paper saying it now estimated that between 20 and 25 per cent of people may have acquired their infection in hospital in the first wave.
The paper does not estimate the number of deaths from hospital-acquired infections but the authors said the “impact on mortality may be high”.
During the first wave hospital patients who unknowingly had Covid (there was a lack of testing capacity) were discharged to care homes in England, leading to deadly outbreaks.
Prof Stephen Powis, the NHS national medical director, told The Telegraph: “We disagree with these claims, since as the paper itself admits, this research makes large speculative assumptions about Covid cases in hospitals which are not actually backed up by data, notably during a period when testing availability was often limited.
"The Office for National Statistics and other data have conclusively demonstrated that the root cause of rising infection rates in hospitals is rising rates in the community, which is why it’s so important the public continue to follow hands, face, space advice."
