Tim Spector, an epidemiologist at King’s College London who runs the Covid Zoe app, said that up to a third of those with cold symptoms could have coronavirus infections.
The professor suggested there are many of these undetected cases in the UK, adding that things could get worse as the omicron strain becomes more widespread in the country.
Without increased self-testing, “we’re going to be compiling that problem much faster than we would need to”, he told Times Radio.
Prof Spector advised the public to work from home if they develop a sore throat or a sniffle, and to self-isolate “at least for a few days with cold-like symptoms”.
“I think everyone needs to be much more aware of a whole range of symptoms and not wait for the loss of smell or taste which may never come, not wait for fever, not wait for that persistent cough,” he added.
The genetic epidemiologist’s comments come as experts estimate there could be more than 1,000 omicron cases in the UK. This is far higher than the 246 infections caused by the variant which had been confirmed by the government as of Sunday.
Professor Paul Hunter, who works at University of East Anglia’s school of medicine, said the latest variant of concern “is spreading rather more quickly than the Delta variant” and could become dominant within the month.
“The big remaining question is actually how harmful it is if you do get Covid with this omicron variant, and that’s the question that we’re struggling to answer at the moment,” he told the BBC.
As the omicron variant spreads, the government has insisted that Christmas parties should go ahead, despite public health warnings from scientists.
“The prime minister has been very clear on this, on Christmas parties. We don’t want people to cancel such events and there is no government guidance to that end,” a No 10 spokesperson said last week.
However, deputy prime minister Dominic Raab has decided his department will hold “appropriate drinks at a small scale” rather than have a large Christmas gathering because of the current coronavirus situation.