Baroness Harding, interim executive chair at the National Institute for Health Protection, said on Wednesday using data from test and trace it could be estimated that around 20,000 individuals with the infection were not following the rules to stay at home.
She was questioned about the figures by Jeremy Hunt, chairman of the Commons health and social care committee, who stressed: “Thousands of people every day is enough to restart the pandemic.”
Baroness Hardling admitted the real number was probably higher than 20,000.
“Could I add a slight complexity to your calculation which actually might well make your number go up a bit, which is that’s the proportion that we know about,” she said.
“My biggest concern about people not isolating is not actually the 20 per cent of people, let’s say, who are not following that instruction.”
She emphasised that her biggest concern was people who feel ill but do not come forward for testing.
Mr Hunt pressed her on the reasons for people flouting the self-isolation rules.
He said: “The people we know about are the people we can do something about and there are thousands of those – 20,000 plus or minus every day who are not self-isolating.
“I’m just wondering why you think that is.”
She responded that one reason was down to communcation and people not understanding and not being clear about what they should and should not do.
“The clearer and simpler the guidance, the easier is it for people to follow it,” she explained.
She added that a second element was people finding it “practically impossible” – not having enough food in the fridge, having care responsibilities, having to collect a prescription.
“Across the country, local authorities have been doing some fantastic work in providing practical support, either directly or through voluntary groups and other third-sector providers,” she explained.
The third reason she gave was the issue of financial support, people who must go out to work as they cannot afford to isolate.
She said it would need to be the case that any financial incentives in place “genuinely drives the right behaviour, rather than any unforeseen consequences”.
Baroness Harding’s fourth reason for people not isolating was mental health – that people find it “really difficult and hard”.
She said there is “undoubtedly more we can do” to help people cope with the mental challenges of self-isolation.
Shadow health secretary Jonathan Ashworth said: “Confirmation that 20,000 people a day sick with Covid are not isolating confirms our repeated warnings that without decent sick pay and support we won’t break chains of transmission.
“With worrying identification of the South African variant in the community and the E484K mutation in the infectious Kent variant it’s now more urgent than ever that this hole in our defences is fixed.”