Senior scientists have called for the UK to expand its official list of Covid symptoms to reduce the number of missed cases and ensure more people know they should self-isolate.
The researchers, who include Prof Calum Semple, a member of the government’s Sage committee of experts, argue the UK’s narrow clinical definition of Covid leads to delays in identifying people with the disease and may miss them altogether, hampering efforts to disrupt the spread of the virus.
Writing in the British Medical Journal, Semple, of the University of Liverpool, along with Dr Alex Crozier at UCL and others describe how Covid patients do not always experience the official UK symptoms of a high fever, a new continuous cough, or a loss of sense of smell or taste early on, or at any time in the course of the disease.
“To reopen society with greater speed and fairness, control of transmission must improve,” they write. “This starts with an expanded and more context appropriate case definition and rests on adaptive, locally grounded, and information-led public health responses.”
While the UK lists only three symptoms for Covid, the US Centers for Disease Control and Prevention lists 11 and the World Health Organization lists 13. The European Centre for Disease Prevention and Control describe a range of symptoms associated with mild-to-moderate Covid-19, the most common being headache, weakness or tiredness, muscle aches, runny nose, appetite loss and sore throat.
Many of these “unofficial” symptoms appear sooner and are more common in young, unvaccinated people who are more likely to pass on the virus, the scientists note.
The researchers concede that expanding the number of symptoms people should look for before taking a test is likely to increase demand for testing and the number who self-isolate. But testing people based on a broader combination of symptoms could spot more cases sooner without putting an unbearable strain on testing capacity, they claim.
Dr Alexander Edwards, associate professor in biomedical technology at the University of Reading, said the scientists raised a valid point about how best to spot cases in the community.
“Many of the symptoms are very common and the best way to judge the likelihood of someone having Covid is a combination of symptoms, their risk of exposure, plus testing. Self-reporting symptoms is especially difficult because even the words we use can be interpreted differently,” he said.
“Spotting people who are infected is just part of the story, however, because unless you can effectively support infected individuals to isolate from others and thereby break the chain of infection, testing alone doesn’t reduce the burden of this disease.”
Jon Deeks, professor of biostatistics at the University of Birmingham, said that while broadening the official symptoms list would increase demand on testing, it would be worthwhile if it led to earlier detection of cases and a good reduction in the number of people spreading it.
“Lateral flow tests are not provided to test people who present with Covid-19 symptoms, but there are many reports on social media of individuals resorting to using them when they are unwell, but not with the key symptoms,” he said.
“They are not well suited as they often fail to identify early stages of infection as they cannot detect low viral loads common at this time. To reduce disease spread, it continues to be important that all those at high risk of infection, which includes many with these symptoms, can access PCR testing as quickly as possible, which requires these changes to be made.”