The seven COVID-19 symptoms to look out for

A new study has identified seven symptoms that, taken together, can improve detection of COVID-19 infection in the community.

Society

Health

One thing we have all learned since the onset of the COVID-19 pandemic is that rapidly identifying and isolating infected individuals and their contacts is key to controlling the spread of the SARS-CoV-2 virus. While a range of associated symptoms have been pinpointed for this purpose, up to now it has been unclear which symptoms are better indicators of the disease. This information is vital when tests are limited. A team of researchers supported in part by the EU-funded EXPANSE project have now identified a set of seven symptoms that, when considered together, maximise detection of COVID-19 in the community. Their findings have been published in the peer-reviewed open-access journal ‘PLOS Medicine’. In countries where there is limited testing capacity, available tests need to be used as efficiently as possible. To identify key symptoms that can facilitate this process, the researchers collected data from more than 1 million people with valid SARS-CoV-2 polymerase chain reaction (PCR) test results between June 2020 and January 2021. The data was collected over eight testing rounds as part of a British study called REal-time Assessment of Community Transmission-1 that uses at-home testing to improve understanding of the pandemic’s progression across England.

The seven symptoms identified

For their research, the team obtained throat and nose swabs from 1 147 370 volunteers aged 5 years and older, 6 450 of whom tested positive. Participants were asked about their symptoms in the week before they were tested. Of the 26 symptoms assayed, 7 were identified as being jointly predictive of PCR positivity for the wild-type virus. Varying only marginally across age groups, these symptoms included loss or change of sense of smell, loss or change of sense of taste, fever, new persistent cough, chills, appetite loss and muscle aches. These symptoms – and to a lesser extent a sore throat – were also found to predict infection with the Alpha (B.1.1.7) variant. “In summary, we show that using a combination of 7 symptoms to determine test eligibility would maximize the case detection rate in the community under testing capacity constraints such as those faced in England between June 2020 and January 2021. This has policy relevance for countries where there is limited testing capacity. We identified the same symptom set for predicting B.1.1.7 which by April 2021 had become the predominant lineage in the UK, US, and many other countries worldwide,” the authors write in their study. The United Kingdom currently uses a restrictive set of four symptoms to determine eligibility for community PCR testing. “These findings suggest many people with COVID-19 won’t be getting tested – and therefore won’t be self-isolating – because their symptoms don’t match those used in current public health guidance to help identify infected people,” observes joint senior author Prof. Paul Elliott of EXPANSE project partner Imperial College London, United Kingdom, in a news release. “We understand that there is a need for clear testing criteria, and that including lots of symptoms which are commonly found in other illnesses like seasonal flu could risk people self-isolating unnecessarily. I hope that our findings on the most informative symptoms mean that the testing programme can take advantage of the available evidence, helping to optimise the detection of infected people.” EXPANSE (EXposome Powered tools for healthy living in urbAN SEttings) is coordinated by Utrecht University, the Netherlands. The 4-year project ends in December 2024. For more information, please see: EXPANSE project website

Keywords

EXPANSE, COVID-19, SARS-CoV-2, pandemic, B.1.1.7, symptom, testing, polymerase chain reaction, PCR, coronavirus