While these broader symptoms were noted in addition to the known or so-called classic symptoms of loss of sense of smell and taste, fever, and a new persistent cough, about 60 percent of people infected reported no symptoms in the week prior to their test, the Imperial College London led Real-time Assessment of Community Transmission (REACT) study unveiled Wednesday.
“These new findings suggest that many people with COVID-19 will not be tested – and therefore will not be self-isolating – because their symptoms do not match those used in current public health guidelines to help identify infected people,” said Professor Paul Elliott, director of the REACT program at Imperial.
“We understand that there is a need for clear testing criteria, and that including many of the symptoms common to other illnesses, such as seasonal flu, can put people at risk of unnecessarily isolating themselves. I hope our findings on the most informative symptoms mean that The testing program can take advantage of the most current evidence, helping to identify more infected people, ”he said.
Swab tests and questionnaires collected between June 2020 and January 2021 as part of the study showed that among these other symptoms, chills, loss of appetite, headache, and muscle pain were most strongly associated with being infected, in addition to the four so-called classic symptoms. .
Having either of these other symptoms or the classic symptoms, alone or in combination, was associated with coronavirus infection, and the more symptoms people had, the more likely they were to test positive.
The study also found that there was variation in symptoms with age. Although chills were associated with positive testing for all ages, headaches were reported in adolescents aged 5-17, appetite loss in 18-54 and 55+, and muscle pain in people aged 18-54. Infected 5-17 year olds were also less likely to report fever, persistent cough, and loss of appetite compared to adults.
The study also examined whether the emergence of the new coronavirus variant in the UK, first identified in Kent, was linked to a different profile of symptoms. While symptoms were broadly similar, loss or change in sense of smell in January of this year compared to November-December 2020 was less predictive of having COVID-19, while the number of people who tested positive with a new persistent cough appeared to have increased.
“As the epidemic progresses and new variants emerge, it is vital that we continue to monitor how the virus is affecting people so that testing programs can meet evolving needs,” said Dr. Joshua Elliott of Imperial College London’s School of Public Health.
“We hope our data will help establish testing guidelines and develop systems that can help better identify people who should undergo a COVID-19 test based on their symptoms,” he said.
People in England are currently encouraged to take a COVID-19 test if they have at least one of four classic symptoms: loss of taste, loss of sense of smell, fever, new persistent cough. This is called “Pillar 2 testing”.
Based on the new findings from the REACT trial, the researchers estimate that current Pillar 2 tests would pick up about half of all symptomatic infections if everyone who qualified were tested. But if the additional symptoms were included, this could be improved to three quarters of symptomatic infections.
The findings, published as a pre-print report before peer review, are part of the ongoing REACT-1 analysis stream led by Imperial College London and conducted in collaboration with Ipsos MORI. The Real-time Assessment of Community Transmission program is funded by the government’s Ministry of Health and Social Care.