Extending the list of symptoms that can be used to allow a Covid-19 test could help to detect around a third more cases, a study has found.
Scientists at King’s College London said that the current method of only giving PCR swab tests through NHS Test and Trace only targets people who are displaying the most common three symptoms of the virus.
These classic symptoms, which are included in NHS guidance, include a loss of taste and smell, a fever, and a new persistent cough.
However, scientists are now calling for this list to be extended to include a wider array of symptoms associated with a Covid-19 infection.
What other symptoms should be included?
Researchers at the university said that extending the list symptoms list to include fatigue, headache, sore throat and diarrhoea would have detected 96 per cent of symptomatic cases, compared to the 69 per cent under the current approach.
Chills, a loss of appetite, headaches and muscle aches have also been identified as additional symptoms of Covid-19 in a separate study conducted by Imperial College London.
Scientists at King’s College London and the Coalition for Epidemic Preparedness Innovations (CEPI) analysed data from more than 122,000 adult users of the Zoe Covid Symptom Study app, which tracks symptoms and the spread of the virus across the UK, who underwent PCR swab testing.
These users reported experiencing a wide array of possible Covid-19 symptoms, and 1,202 had a positive PCR test within a week of first feeling ill.
However, data found that only giving PCR swab tests to people with the three classic symptoms of a cough, fever, or loss of taste and smell would have missed around a third of cases, detecting only 69 per cent of symptomatic cases.
If the criteria was extended to include the four additional symptoms of fatigue, headache, sore throat and diarrhoea, testing in the first three days of illness would have instead picked up significantly more cases, up to 96 per cent.
Headache and diarrhoea common early symptoms
In the early stages when people are most infectious, 31 per cent of people who are ill with coronavirus do not experience any of the classic three symptoms, according to the data.
Researchers found that users of the symptom app were more likely to select headache and diarrhoea within the first three days of infection, and a fever during the first seven days.
A cough or shortness of breath were also reported by 46 per cent of people who tested positive for Covid-19 within the first three days of infection.
Results indicate how people can experience different symptoms at different times during the course of infection, suggesting the symptoms list should not be limited to just three key things.
Professor Tim Spector from King's College London said: "We've known since the beginning that just focusing testing on the classic triad of cough, fever and anosmia misses a significant proportion of positive cases.
"We identified anosmia as a symptom back in May and our work led to the government adding it to the list, it is now clear that we need to add more.
"By inviting any users who log any new symptoms to get a test, we confirmed that there are many more symptoms of COVID-19.
"This is especially important with new variants that may cause different symptoms. For us, the message for the public is clear: if you're feeling newly unwell, it could be Covid and you should get a test."