Hundreds of people were infected with coronavirus while in hospital during the first wave of the pandemic, according to scientists advising the government.
In a new document published by the Scientific Advisory Group for Emergencies (Sage) on Friday, figures suggest at least 8.8 per cent of Covid hospital cases in England in the first peak may have been what are known as nosocomial, or hospital-acquired, infections.
It said that between February 2 and July 26 there were about 7,906 cases of Covid-19 infections where patients tested positive 15 or more days after hospital admission.
The “least conservative” estimate suggests as many as 40% of hospitalised Covid patients in first wave – or 36,152 people – caught it after being admitted.
But the NHS said rising infection rates in hospitals came as cases increased in the community.
The infections were among people attending hospital for treatment for another illness, or who developed Covid shortly after being discharged and then ended up back in hospital.
Some of the cases were only suspected, while others were confirmed by process of elimination.
The experts said that while the proportion of Covid-19 cases linked to hospital transmission is considerable, this is relatively small at a population level.
The undated document said: “A simple calculation assuming 5% of infections are hospitalised and of these hospital cases, if 25% are due to nosocomial infection, the complete prevention of nosocomial transmission would have led to approximately 1% impact on the number of infections in the English epidemic overall.
“However, since hospitalised patients tend to be old and/or frail, the impact in terms of morbidity and mortality would nonetheless be expected to be substantial.”
Commenting on the paper, NHS national medical director, Professor Stephen Powis, said: “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 for Covid-19 was often limited.
“The ONS 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.”