A new study published in the journal eLife investigating data from Addenbrookes Hospital in Cambridge, England, found that 3 percent of frontline National Health Service (NHS) workers were infected with Covid-19 without realizing. The findings indicate that it’s likely thousands of healthcare workers have been practicing during the outbreak whilst being actively contagious, highlighting the importance of testing even in asymptomatic individuals.
The study tested more than 1,200 NHS workers at the Addenbrooke’s Hospital using swabs and found that of the 1,000 deemed fit for work, 3 percent tested positive for the SARS-CoV-2 virus. Those working with an active infection reported either mild or no symptoms. Under the assumption that healthcare workers at the Addenbrooke’s Hospital are representative of the wider population, the findings indicate that of the millions of NHS workers in the UK, around 15,000 could be practicing while actively infectious.
“We were interested in testing two groups of healthcare workers,” said Dr Dominic Sparkes, an infectious diseases specialist at Addenbrookes Hospital and one of the authors on the study in an interview with IFLScience. “Those that had symptoms of Covid-19 and those that were asymptomatic and continuing to work.
"Our research has shown that of those health care workers who were asymptomatic, 3 percent were positive for SARS-CoV-2. These workers could, therefore, be unknowingly spreading the disease. The only way to find these people is by frequent and widespread testing, which is what we are doing in Addenbrooke’s hospital in Cambridge. Discovering who has the virus and isolating them is the only approach we have currently to break transmission and control the disease and this is why it is so important to test as widely and as often as we can.”
The news comes as the UK continues to underdeliver on test target numbers issued by the government. Without adequate testing, carriers of the pathogen experiencing only mild disease will continue to come into close contact with patients who may be at higher risk of succumbing to Covid-19.
“All physicians in our hospital wear appropriate personal protective equipment (PPE) including masks when they see any patient, which helps to reduce the transmission of the virus to patients if a health care worker were to have asymptomatic infection,” Dr Sparkes continued. “However, it is really important that those who do have the disease are isolated to protect not only the patients but other staff members.”
One of the key factors in Covid-19's spread has been the R rate, which indicates the average number of people an infected person will pass the pathogen on to. Keeping the R rate down is vital in slowing the spread – which is where social and physical distancing plays a key role. If asymptomatic but infected healthcare workers are still going into hospitals, these staff members will go on to infect others in the workplace who may become ill enough to have to take time off work. This highlights the importance of preventing onward transmission by isolating these asymptomatic individuals as it will lead to more staff at work overall.
"It would also be unethical to allow people who could infect others to work and risk spreading it," continued Dr Sparkes. "Preventing transmission is the key to tackling this disease, which is why we need lockdown and social distancing, as well as regular testing in hospitals, to prevent them from becoming hubs of infection.”