A study of more than one million people in England has revealed additional symptoms that are linked with having the coronavirus.
Chills, loss of appetite, headaches and muscle aches have been reported as symptoms.
This is in addition to the classic symptoms - loss of sense of smell and taste, fever and a new persistent cough.
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The research is based on swab tests and questionnaires collected between June 2020 and January 2021 as part of the Imperial College London-led React study.
Having any of these other symptoms or the classic ones, either alone or in combination, was associated with infection with the coronavirus and the more symptoms people showed the more likely they were to test positive.
The study also found that there was variation in symptoms with age.
While chills were linked with testing positive across all ages, headaches were reported in young people aged five to 17, appetite loss in 18 to 54 and 55+, and muscle aches in people aged 18 to 54.
Infected five to 17-year-olds were also less likely to report fever, persistent cough and appetite loss compared with adults.
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Professor Paul Elliott, director of the REACT programme at Imperial, said: “These new 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.
"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 most up-to-date evidence, helping to identify more infected people.”
