The arguments for regularly testing NHS staff are “overwhelming,” said Dr. Charles Swanton, a cancer scientist at the Crick Institute.
His team identified positive NHS staff members at the peak of the pandemic who were “completely asymptomatic”.
But the study could not show whether these symptomless employees passed on their infections to others.
The Ministry of Health and Welfare said it was “guided by the evidence” on routine testing.
Dr Swanton said that if the prevalence of infection among health workers is now low, routine screening would be necessary “before a second wave”.
The study health workers were swabbed between March 26 and April 8, at the height of the pandemic, and then followed for a month.
Of the 200 staff at University College London Hospital tested, 36 were positive at baseline, of which 16 (38%) reported no discernible symptoms at the time of the test or at any time afterward.
For the 20 people who developed symptoms, they developed on average four days after the positive test.
The same people were also tested for antibodies in their blood, suggesting a past Covid infection.
At the end of the study period, 45% (87 staff members) had developed antibodies.
This level of exposure to the virus among healthcare workers was much higher than expected and that previous studies had suggested, said Dr. Swanton. “The arguments for asymptomatic testing for healthcare professionals seem overwhelming. ”
A government spokesperson said, “We have discussed with SAGE the appropriate frequency of repeat testing, as the NHS Trusts continue to test asymptomatic front-line staff regularly and strategically. ”
People working in patient and resident roles in health care and social services were six times more likely than the general population to test positive for the coronavirus, according to figures released by the Office for National Statistics Tuesday.
Evidence suggests that people without symptoms are capable of transmitting the virus, but establishing the extent of their role remains difficult.
On June 11, the government’s science emergency advisory group said infectivity “correlates with duration of illness / severity” – in other words, it appears that people with symptoms are more likely to transmit disease.
This does not mean that asymptomatic people do not transmit the disease at all.
But also, the fact that a large proportion of positive tests concern people without symptoms does not mean that a large number of infections are spread by these people.
It is believed that only 10-15% of people are responsible for about 80% of infections.
A number of NHS leaders have called for routine staff testing at least once, if not twice a week, to make sure they are unknowingly carriers.
Asymptomatic tests are currently available to treat home staff and residents.
A pilot launched Thursday will look at testing other “high contact” professions, such as taxi drivers and symptomless vendors.