Cambridge Study: 3% Of Hospital Staff Unknowingly Carrying COVID-19

CAMBRIDGE, England — The United Kingdom is among the hardest hit nations regarding COVID-19 infections and deaths. Now, a new study out of Cambridge University suggests that not enough is being done in U.K. hospitals to identify hospital staff infected with the coronavirus.

Researchers tested 1,200 supposedly fit-for-duty National Health Service staff members at Addenbrooke’s Hospital last month, and 3% ended up testing positive for COVID-19.

All patients admitted to British hospitals are immediately screened for the coronavirus. However, NHS staff, including patient-facing workers like doctors and nurses, are only tested for COVID-19 if they display relevant symptoms. We all know by now that individuals can be contagious carriers of the virus without exhibiting obvious or even subtle symptoms.

Among the 3% who tested positive, roughly 20% didn’t feel any symptoms at all, 40% admitted to very mild symptoms that they had shrugged off, and another 40% said they had felt some passing symptoms over a week ago that had gone away.

“Test! Test! Test! And then test some more,” proclaims senior author Dr. Mike Weekes, of the Cambridge Institute of Therapeutic Immunology and Infectious Disease, in a release. “All staff need to get tested regularly for COVID-19, regardless of whether they have any sort of symptoms – this will be vital to stop infection spreading within the hospital setting.”


Next, the research team wanted to better understand how the coronavirus is spreading through hospitals. So, they compared rates of infection among workers assigned to “red” areas, or wards specifically caring for COVID-19 patients, to infection rates in “green” COVID-19 free hospital areas. Predictably, despite all staff wearing PPE in red areas, workers in COVID-19 wards were three times more likely to contract the virus themselves than their peers operating in green areas.

That being said, it’s unclear if those higher transmission rates in red areas are due to patients spreading the virus to NHS staff. Those healthcare workers may have spread COVID-19 amongst themselves, or picked the virus up outside the hospital altogether. Red zone workers were tested for coronavirus earlier than green zone workers, and closer to when lockdown measures were first introduced in the United Kingdom, so it’s plausible that their higher infection rates were due to COVID-19 being more widespread at the time.

Still, if the 1,200 worker sample taken by Cambridge is accurate, that means that as many as 15,000 NHS workers were reporting for work in the month of April while infected with COVID-19. That figure could be even higher in certain hospitals where PPE supplies have proven inadequate.

The study is published in eLife.

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