People who have cold-like symptoms in London are more likely to have Covid than a cold, according to the scientist behind the Zoe coronavirus symptom tracker app.

Prof Tim Spector told BBC Radio 4’s Today programme that most of the symptoms of Omicron were the same as those of a common cold, including headaches, sore throat, runny nose, fatigue and sneezing.

Spector urged people with cold symptoms – and not just the classic Covid symptoms – to take a test. “Things like fever, cough and loss of smell are now in the minority of symptoms we are seeing,” he said. “Most people don’t have classic symptoms.”

He added: “In London, where Covid is increasing rapidly, it’s far more likely to be Covid than it is to be a cold. We’re seeing doubling in the numbers equivalent to what’s being seen elsewhere, every two and a half days.”

Omicron is already the dominant Covid variant in London and will soon account for nearly all infections.

Separately, a government science adviser has suggested that panic around the oncoming Omicron wave is unjustified. Speaking in a personal capacity, Prof Robert Dingwall, a government Covid adviser from Nottingham Trent University, told the Daily Telegraph: “The Omicron situation seems to be increasingly absurd. There is obviously a lot of snobbery about South African science and medicine but their top people are as good as any you would find in a more universally developed country. They clearly don’t feel that the elite panic over here is justified, even allowing for the demographic differences in vulnerability – which are probably more than cancelled by the higher vaccination rate.

“My gut feeling is that Omicron is very much like the sort of flu pandemic we planned for – a lot of sickness absence from work in a short period, which will create difficulties for public services and economic activity, but not of such a severity as to be a big problem for the NHS and the funeral business.”

A study looking at 78,000 Omicron cases in South Africa found that the risk of hospitalisation was 29% lower compared with the original Covid-19, and 23% lower than the Delta variant, with vaccines holding up well. Fewer people with Omicron needed intensive care, with just 5% of cases admitted to ICU compared with 22% of Delta patients, the study found.

Dingwall’s comments were at odds with those of the papers’s authors, who warned that South Africa’s experience of Omicron might not be a reliable indicator for how the Omicron outbreak unfolds in other countries. And the head of the World Health Organization, Tedros Adhanom Ghebreyesus, said on Tuesday it would be “wrong for people to consider Omicron as mild”.

Prof Paul Hunter, of the University of East Anglia, said Dingwall’s comments were “going really out on a limb” and it was still too early to say how case numbers would translate into hospitalisations in the UK.

Hunter said he was optimistic that immunity against severe disease would hold up quite well, but added: “A million cases of Omicron a day would be horrendous even if it was just as bad as flu.”