Cast your mind back – if you can bear it – to the end of 2020, when the UK and many other countries were in the throes of their worst surge of covid-19 deaths of the pandemic.
It was known that the SARS-CoV-2 coronavirus was spreading within hospitals, weakening people who were already sick and sometimes killing them. There have been previous studies of the problem, but the most comprehensive analysis yet has confirmed that virus transmission was happening at an alarming scale.
The new study found that up to 1 in 50 people admitted to hospital during England’s second wave caught the coronavirus there. Some say this shows hospitals should be clamping down harder on the spread of covid-19 today.
On the other hand, most people now have some immunity to the virus and many health bodies say covid-19 is no longer a public health emergency. So, should northern hemisphere countries be stepping up coronavirus precautions in hospitals as winter approaches?
The new study, by Ben Cooper at the University of Oxford and his colleagues, analysed covid-19 cases between June 2020 and March 2021 from 365 hospitals in England. People were classed as having definitely or probably caught the virus in hospital if they tested positive after being in hospital for more than seven days.
After adjusting the figures to take account of those who would have been missed by this approach, for instance because they were discharged before testing positive, the team calculated that between 1 and 2 per cent of people admitted to hospitals in England during this period caught the virus there. “That’s a horrible statistic,” says Tom Lawton at the Bradford Institute for Health Research, UK.
But not all hospitals experienced the same amount of transmission. People were more likely to catch the virus in buildings with less air volume per bed – in other words, higher bed density and lower ceilings – and fewer single rooms. While hospitals cannot be rebuilt overnight, this shows the value of trying to reduce airborne spread, for instance by using air filtering machines, says Christina Pagel at University College London. “We may not be able to suddenly turn our hospitals into single-bed palaces, but we can make their air cleaner.”
But Cooper says we should be cautious about assuming the results can be translated directly into policy recommendations, for two reasons. The first is that populations now have more immunity to covid-19. “Almost everyone’s been infected or vaccinated or both,” he says.
The other issue is health systems have to weigh up multiple competing priorities for their resources. “If you’re spending millions of pounds on better masks or [air filters], then that’s resources taken away from somewhere else,” he says.
Some hospitals in England have also recently come under fire for advising staff with respiratory symptoms that there is no need to test for covid-19, unless they work on wards where people may have very weak immune systems, such as those treating people with cancer.
But any kind of stricter testing policy could also have trade-offs, says David Oliver, a doctor based in Reading, UK. If hospitals tell staff who feel healthy or have only minor symptoms to stay home if they test positive, that lowers their capacity to provide healthcare, at a time when they are under great pressure to reduce waiting lists.
If the latest study tells us anything, it is that interventions such as masking or stricter isolation strategies should be tested in randomised trials, in the same way that new medicines or vaccines are. Even simply improving data collection on different hospitals’ strategies would allow some tentative conclusions to be drawn about the best course of action in future, says Cooper. This would be invaluable intelligence for when the next pandemic hits.