Feeling unwell? It could be COVID-19, so get a test

February 17, 2021

If you find you’re suddenly unwell, it could be COVID and you should get a test. That’s the message from our latest analysis of data from the ZOE COVID Symptom Study app.

Right now, only people experiencing any of the ‘classic three’ symptoms of cough, fever and loss of smell are eligible for an NHS PCR swab test to confirm COVID-19 infection.

But data from the ZOE app shows that 31% of people who are ill with COVID-19 don’t have any of these three signs in the early stages of the disease.

Our latest findings, which have been published in the Journal of Infection, suggest that only testing people with the three classic symptoms may have led to hundreds of thousands of cases in the UK being missed over the course of the pandemic.

Simply adding fatigue, sore throat, headache and diarrhoea to the classic three symptoms for NHS testing would detect many more cases, helping to stop the spread of the virus and bring the pandemic to an end.

There’s more to COVID-19 than cough, fever and loss of smell

To find out which symptoms are most likely to indicate that someone is infected with COVID-19 and should have a PCR test, our research colleagues at King’s College London and the Coalition for Epidemic Preparedness Innovations (CEPI), analysed data from more than 122,000 UK adult users of the ZOE COVID Symptom Study app who reported experiencing any potential COVID-19 symptoms, 1,202 of whom reported a positive PCR test within a week of first feeling ill.

We found that testing people with any of the three ‘classic’ symptoms would have spotted 69% of symptomatic cases, with 46 people testing negative for every person testing positive. 

However, testing people with any of seven key symptoms - cough, fever, anosmia, fatigue, headache, sore throat and diarrhoea - in the first three days of illness would have detected 96% of symptomatic cases, with 95 negative tests for every positive one.

When should you get a COVID-19 test?

“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 persuaded the Government to add anosmia to the list back in May and now it is clear we need to add more,” says Professor Tim Spector, ZOE COVID Symptom Study project lead.

“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. The message for the public is clear: if you’re feeling newly unwell, it could be COVID and you should get a test.” 

ZOE COVID Symptom Study app contributors are offered a test if they report any of the potential symptoms of the disease, including:

  • Severe fatigue
  • Headache
  • Change or loss of smell (anosmia) or taste
  • Persistent cough
  • High temperature/fever
  • Diarrhoea
  • Unusual pains in the chest, abdomen or muscles
  • Sore throat or a hoarse voice
  • Severe shortness of breath
  • Sudden confusion (delirium)
  • Skipping meals
  • Skin rash
  • Changes to the tongue or mouth ulcers.

If you start feeling ill with any of these symptoms, it could be COVID-19. You should self-isolate, download the ZOE COVID Symptom Study app, log your symptoms and get a test. 

We’re now calling on the Government to expand NHS PCR swab testing to people experiencing a wider range of symptoms, to help detect and contain more cases and end the pandemic.

“When PCR testing was scarcely available, it made sense to restrict it,” says Dr Claire Steves, Reader at King’s College London and lead scientist on the ZOE COVID Symptom Study app.

“Now in the UK we have plenty of tests available, thanks to so much effort by labs all over the country, and every positive person detected could save lives. We urge the Government to expand the testing criteria so that anyone with new symptoms that might be COVID-19 should be able to get a test to help stop the spread of the virus.” 

Stay safe and keep logging.

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