Coronavirus has "largely gone out" of the UK population outside hospitals and care homes, a professor of epidemiology has told Sky News.
Tim Spector, whose COVID Symptom Study app has been downloaded more than three million times, said the official number of confirmed cases – just over 211,000 – was "very artificial" because it is the "only number they've been able to test, or get to hospital".
"We think the real number is in the millions," he said.
But numbers are falling, he added, saying: "It seems to be that it's largely gone out of the population, where rates are really low."
The apparent disparity between the general population and hospitals and care homes is "probably due to residual infections they haven't been able to get rid of, particularly in care homes", Prof Spector said.
He also claimed there are 13 or 14 symptoms associated with COVID-19.
Apart from a fever and persistent cough, other signs to look out for include acute muscle pain and, in the elderly, gastric problems, diarrhoea, confusion and even hypothermia.
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Children and young people have been getting skin rashes with coronavirus, Professor Spector said.
There is an "increasing list of these rather strange conditions that we really need to collect in order to capture the real disease", he continued.
Failure to do so would mean "missing it in the population when it starts to come back", according to Prof Spector.
If all the symptoms were collected in an algorithm, "you can predict nearly as well as a test whether someone's infectious or not", he said.
Prof Spector, from King's College London, added that the official focus on only a fever and persistent cough is "rather rigid".
He said that without those two signs of the virus, "no one takes you seriously – you don't self-isolate, and you don't get a test".
He added: "There's now overwhelming evidence that's not true – many other countries have changed their definitions."