Infection rates for SARS-CoV-2 among NHS workers were no higher among those treating patients than for staff in non-clinical roles, researchers found.
The authors of the study said the findings might offer some reassurance on isolation protocols and the effectiveness of personal protective equipment (PPE) to health workers on the front line.
The research also underlined how testing all symptomatic NHS workers for COVID-19 was possible during a pandemic, helped maintain staffing levels, and provided reassurance to individuals and their families.
Tests on Hospital Workers, GPs, and Ambulance Staff
The study, published as a letter in The Lancet, described how combined nose and throat swab tests for SARS-CoV-2 were carried out on 1654 symptomatic staff at Newcastle upon Tyne Hospitals NHS Foundation Trust.
The tests, which were performed between 10th and 31st March, involved mainly hospital employees but also included local GPs and members of the North East Ambulance Service.
Overall, SARS-CoV-2 was detected in 14% of the tests.
Test results were divided into three groups:
Directly patient-facing, including nurses, doctors and porters=
Non-patient facing but at a potentially higher risk of exposure, such as laboratory staff
Non-clinical workers, including administrative workers
Screening criteria initially prioritised frontline healthcare staff which meant that most, 81%, were in group 1, with 8% in group 2, and 11% in group 3.
Hospital Transmission 'Not Necessarily a Factor'
The researchers expected to find higher rates of infection in patient-facing staff. However, actual results showed infection rates were:
15% among directly-facing healthcare workers
16% among non-patient facing staff
18% among non-clinical workers
"What that mostly reflects is that the circulation was mostly in the community at that time and that in-hospital transmission wasn't necessarily a factor," co-author Dr Lucía Pareja-Cebrián, a microbiologist, told Medscape News UK.
This finding was consistent with observations in China, where healthcare staff testing was widespread, the researchers said.
They conceded some limitations with the data. These included being unable to identify staff roles for more than a third of those tested, and the small number of non-clinical staff tested.
Dr Pareja-Cebrián, director of infection prevention and control within Newcastle Hospitals NHS Foundation Trust, said they were among the first to conduct staff testing for SARS-CoV-2 in order "for our staff to feel confident in that if they were symptomatic, it was either coronavirus or it wasn't coronavirus, because there's lots of viruses circulating at any given time and the symptoms could be corresponding to anything else".
She said it "provides that level of assurance that you are wearing the right PPE, you're following the processes and procedures that we have set up, following Public Health England, and you continue to be safe, and you haven't acquired it in a hospital setting".
Lead author Dr Christopher Duncan, research fellow at Newcastle University and honorary consultant in infectious diseases within Newcastle Hospitals, said: "An efficient and robust system of testing has enabled 1414 health care workers to return more rapidly to NHS service in Newcastle in the last 3 weeks, the vast majority returning directly into patient care."
His comments coincided with a call by the British Medical Association (BMA) for the Government to improve availability of COVID-19 testing for healthcare workers.
It estimated that across England, Scotland, and Wales nearly 100,000 healthcare workers are currently self-isolating due to COVID-19, with many not knowing if they have the virus and therefore unable to go to work.
"There is little clarity at local and regional levels for staff and their family members about how to get tested and we need to see better coordination of testing and far greater availability if we want to see any real chance of confidently and safely returning thousands of staff back to frontline care," said Prof Dame Parveen Kumar, the BMA board of science chair.
Today's study in The Lancet also provided "several important insights into the COVID-19 epidemic in England", the authors said.
Initially, rates of positive tests for COVID-19 were relatively low, at 5% on 10th - 11th of March. They then rose steadily throughout the testing period, reaching 20% on 30th - 31st March.
There was a period of exponential growth from the 10th to around the 24th of March, with a doubling time of 2.2 days.
However, from around the 24th March, a flatter rate of increase was noted, consistent with the implementation of social distancing measures, including school closures on the 20th and closures of pubs, restaurants, and non-essential shops on the 23rd.
"Although it is not possible to assign causality, it seems plausible that these measures have affected community transmission of SARS-CoV-2 in our region," the researchers said.