Nine out of 10 health and care workers who caught the coronavirus got it at work, according to a report published today.
And one in five patients hospitalised with Covid-19 had caught the virus while on a ward, raising concerns about the spread of the disease inside hospitals.
The report, by scientists on the Data Evaluation and Learning for Viral Epidemics group (DELVE), added that at least one in ten of all coronavirus cases diagnosed in England in May were found in healthcare workers.
Researchers say transmission in homes and hospitals — which often happens between people with no symptoms — acts like a ‘revolving door’ with outbreaks in the community, with both feeding off each other.
The report estimated an extra one per cent of cases in May were among hospital patients who caught the virus in hospital.
And another six per cent were in care home residents, the researchers said.
They pointed out that data suggests Covid-19 infection is six times more likely for healthcare workers than it is for the general population, with Office for National Statistics testing suggesting 1.87 per cent of healthcare workers would test positive compared to 0.32 per cent of the general population.
Inadequate protective equipment, not enough testing, not separating patients well enough and staff not following social distancing may all have been behind the spread, the experts suggested.
The Royal Society’s report, titled ‘Hospital and health care acquisition of COVID-19 and its control’, investigated the spread of coronavirus in hospitals and care homes in England.
It was carried out by the Data Evaluation and Learning for Viral Epidemics committee (DELVE).
It tried to work out the scale of the spread – nosocomial infection – and reasons why it had happened and how to prevent it in future.
The researchers said it was important to understand the spread among health and care workers because it contributed to cases in the community as well, and vice versa.
The report said: ‘Infections in hospital have important implications for infection outcomes (hospitalised patients and some staff are at higher risk), workforce planning (healthcare workers being unable to work during peak pressure periods), and amplification of community transmission (through discharge of infectious patients and transmission to families and other contacts from healthcare workers and patients).’
The report referenced a study published by Public Health England in May which predicted 89 per cent of Covid-19 cases among healthcare workers were spread inside hospitals.
And approximately 20 per cent of infections in hospital in-patients had been caught by the patient while they were in hospital for something else, it said.
Data from between April 26 and June 7, the report said, revealed that at least 10 per cent of all Covid-19 infections were in health and care workers.
This period did not include the peak of the crisis, which was at the end of March and the start of April.
But health workers made up a smaller proportion of all cases during that time, the report said, when the virus was more widespread among members of the public.
It estimated that the peak of all in-hospital infections was at the same time as the national peak, but hospitals made up the greatest proportion at the start of May, when it was between 10 and 20 per cent.
Professor Anne Johnson, from University College London, said: ‘Hospital-acquired infections amplify community spread…. There is a revolving door from the hospital to the community and back again,’ the Evening Standard reported.
Health and care workers were likely to catch the virus at work while caring for people with Covid-19, it said, and then to take it home and spread it to their families.
Or on the other hand, they were at risk of spreading it to more people if they caught it outside of work, because they come into contact with so many people.
The report included one case study of a hospital worker in Germany who went into work with a fever and infected 28 colleagues, 13 patients and seven visitors.
In that case the uncontrolled spread had been blamed on a lack of social distancing and protective equipment (PPE), as well as the infected worker not staying at home.
Social distancing, PPE and generally sub-standard hygiene practices had caused in-hospital spread around the world, the report said.
It appeared to include Britain but did not single out specific causes in NHS hospitals.
Some of the reasons the virus appeared to spread so quickly in hospitals and care facilities were, the report said, inadequate hand washing, a failure to properly disinfect surfaces, lack of appropriate physical distancing, not separating infected and non-infected patients, and rotating staff through different areas of hospitals.
They also said that more testing and tracing would be needed in future to control the spread of the virus among healthcare workers.
In recommendations for reducing infections in the future the experts recommended widespread, rapid testing for all staff in hospitals, not just doctors and nurses.
They also called for better surveillance and data for hospital-acquired infection, outbreak investigations for when cases did appear, and more research into cost-effective ways of reducing the spread of the disease.
Professor Johnson said: ‘We now better understand the risks of COVID-19 transmission within hospital and care settings although improved data are needed.
‘As in many countries, outbreaks have occurred and continue to occur, though renewed prevention efforts are now in place.
‘Now we need to learn from our experience and use our greater understanding of how the pandemic has played out, to ensure we are better prepared to prevent and manage new outbreaks and a potential second wave, protecting everyone.’