It comes as the latest UK figures show that there have been 13,729 deaths – a rise of 861 in a day – with 103,093 cases of coronavirus.
The new research measures symptoms among a large sample of the population. This means it is likely to detect earlier changes in disease patterns, with hospitalisation among the most severe cases normally falling around two weeks after signs such as coughs and fevers first emerge.
Previous research from the same study recently suggested that losing the senses of taste and smell may be the most reliable symptom of coronavirus. Scientists found that almost 60 per cent of people with the virus had lost those senses, compared with just 32 per cent who reported suffering a fever.
Currently, people in the UK are instructed to self-isolate only if they have a persistent cough, a high temperature or both.
Lead researcher Professor Tim Spector from King’s College London, said: “It’s very reassuring to see that the number of predicted symptomatic Covid cases is continuing to fall day on day across the UK but, with deaths still high, this is definitely not the time for complacency.
“We believe our population’s symptoms are changing around two weeks before most people are admitted to hospital.”
Prof Spector said the data suggested there is still a large number of infectious people in the UK with mild symptoms, meaning it would be premature to lift the lockdown.
It came as NHS England statistics showed that April 8 had seen the highest coronavirus death toll in England’s hospitals to date, suggesting the rate of deaths could soon fall. However, officials have warned that data from recent days, including the Easter weekend, may not be up to date.