Testing suggests 3% of NHS hospital staff may be unknowingly infected with coronavirus


13-05-2020
Hospital staff  Credit: Hospital CLÍNIC

Hospital staff may be carrying SARS-CoV-2, the coronavirus that causes COVID-19 disease, without realising they are infected, according to a study by researchers at the University of Cambridge.

Patients admitted to NHS hospitals are now routinely screened for the SARS-CoV-2 virus, and isolated if necessary. But NHS workers, including patient-facing staff on the front line, such as doctors, nurses and physiotherapists, are tested and excluded from work only if they develop symptoms of the illness. Many of them, however, may show no symptoms at all even if infected, as a new study published in the journal eLife demonstrates.

The Cambridge team pro-actively swabbed and tested over 1,200 NHS staff at Addenbrooke’s Hospital, Cambridge University Hospitals NHS Foundation Trust, throughout April. The samples were analysed using a technique called PCR to copy and read the genetic information of material present on the swab, producing a colour change whenever the coronavirus was present in a specimen. At the same time, staff members were asked about relevant coronavirus symptoms.

Of the more than 1,000 staff members reporting fit for duty during the study period, 3% nevertheless tested positive for the coronavirus. On closer questioning, around one in five reported no symptoms, two in five had very mild symptoms that they had dismissed as inconsequential, and a further two in five reported COVID-19 symptoms that had stopped more than a week previously.

To probe routes of possible transmission of the virus through the hospital and among staff, the researchers also looked at whether rates of infection were greater among staff working in “red” areas of the hospital, those areas caring for COVID-19 patients. Despite wearing appropriate personal protective equipment (PPE), “red” area staff were three times more likely to tested positive than staff working in COVID-19 free “green” areas. It’s not clear whether this genuinely reflects greater rates of transmission from patients to staff in red areas. Staff may have instead transmitted the virus to each other or acquired it at home. Staff working in the “red” areas were also swabbed earlier in the study, closer to when the lockdown was first initiated, so the higher rates of infection in this group might just be a symptom of higher rates of virus circulating in the community at the time.

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Image: Hospital staff

 

Reproduced courtesy of the University of Cambridge

 

The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.

University of Cambridge (cam.ac.uk)