Chills, a loss of appetite, headaches and muscle aches could be additional symptoms of coronavirus, a study suggests.

This is in addition to the classic symptoms – losing your sense of smell and taste, a fever and a new persistent cough.

A study of more than one million people in England revealed the extra symptoms that are linked with having Covid-19.

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.

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

Having any of the other symptoms or the classic ones, either alone or in combination, was associated with infection with Covid-19 and the more symptoms people showed the more likely they were to test positive.

But around 60% of infected people did not report any symptoms in the week leading up to their test.

The study also found that there was a 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 and appetite loss was reported more in 18-54 year olds and those aged 55 and over.

Muscle aches were mostly reported in people aged between 18 and 54.

Infected five to 17 year olds were also less likely to report fever, a persistent cough and appetite loss compared with adults, according to the study.

People in England are currently encouraged to get a Covid-19 test if they have any of the classic symptoms.

The researchers estimate that if everyone who had classic symptoms were tested, it would pick up around half of all symptomatic infections.

But they say that if the additional symptoms were included, this could be improved to three-quarters of symptomatic infections.

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.”

The study, which has not yet been peer-reviewed, also looked at whether the emergence of the UK’s new coronavirus variant, first identified in Kent, was linked with a different profile of symptoms.

Researchers looked at self-reported symptoms and swab test results collected for the React study in November – December, when PHE estimated the variant made up around 16% of infections.

They compared this with similar data collected in January, when an estimated 86% of infections were from the variant.

While, according to the study, symptoms were broadly similar – in January, compared to November – December, loss or change to one’s sense of smell was less predictive of having Covid-19.

But the proportion of people testing positive with a new persistent cough appeared higher, in keeping with findings from the Office for National Statistics.