3 main symptoms ‘don’t show up in 80% of cases’

EIGHT in ten of those infected with coronavirus do not have any of the main symptoms, a major study has revealed. It also showed that more than three quarters have no symptoms whatsoever.

Scientists said the findings show testing strategies must be changed to pick up ‘silent’ infections in those who may be unwittingly spreading the virus.

The researchers at University College London found that 6 per cent of individuals who become infected do not have a fever, cough or loss of smell when they test positive.

The study used data from 36,061 volunteers tested by the Office for National Statistics coronavirus infection survey. Of those who had a positive test result, less than a quarter had any symptoms on the day they were swabbed. And just 14 per cent had one of the three main signs.

The study, published in the journal Clinical Epidemiology, concluded: ‘Covid-19 symptoms are a poor marker of infection.

‘To capture “silent” transmission … test programmes should involve frequent and widespread testing of all individuals, not just symptomatic cases, at least in high-risk settings or specific locations where many people work or live close together such as meat factories or university halls.’ Lead author Professor Irene Petersen said the findings highlight that large numbers may be spreading the virus while asymptomatic.

She said: ‘You may have a lot of people who are not self-isolating because they didn’t know that they are positive.’

Students should be tested regularly, particularly before going home for Christmas, she said, adding: ‘I think you could seed a lot of new infections around Christmas – you’re indoors, you sit around the table.’

Tim Spector, professor of genetic epidemiology at King’s College London, warned that other virus symptoms, including headache, fatigue, and diarrhoea, are often overlooked.