Evidence doesn’t show 20,000 people ‘sick with Covid’ fail to self-isolate every day

“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.”

It has been incorrectly claimed that 20,000 people “sick with Covid-19” are failing to isolate every day. This is based on comments made by Baroness Dido Harding, chair of the Test and Trace programme. However, Baroness Harding was not just referring to people who have tested positive for Covid-19, but to anyone advised to isolate. The figure was also a very rough estimate.

During an appearance before the Science and Technology Committee on 3 February, Baroness Harding faced questions from Jeremy Hunt MP about the number of people who fail to isolate after being asked to by Test and Trace.

Baroness Harding based her response—which she said came with many caveats—on a survey from University College London (UCL), which estimates that 80% of UK adults are isolating for the recommended 10 days or more when they are told they have come into contact with someone with symptoms of Covid-19. 

She said that in the previous week around 700,000 Covid “cases and contacts” were identified (meaning the number of people who tested positive for Covid, and the number of people asked to isolate after coming into contact with someone with Covid), which would roughly equate to 100,000 a day. So if 20% of these did not properly isolate, this would equate to 20,000 people every day. 

It is wrong to claim that the 20,000 figure discussed by Baroness Harding and Mr Hunt is made up solely of people who have tested positive and failed to isolate, as suggested by Mr Ashworth and others on Twitter. At no point in her discussion with Mr Hunt did Baroness Harding suggest that 20,000 people a day who are “sick with Covid” are failing to isolate. Their 20,000 estimate was of people “not isolating in the way that we need them to”, which would include those asked to isolate because they have been in contact with someone with Covid even if they are not unwell themselves. 

Baroness Harding’s estimate was just that: a very rough estimate. The UCL survey says that while 80% of those who are told they have come into contact with someone with symptoms of Covid-19 isolate for the full 10 days, just 62% of those who develop symptoms themselves do the same. The survey did not contain data on the self-isolation habits of confirmed coronavirus cases, so it is not possible to create a very reliable estimate of the number of Covid “cases and contacts” who are not self-isolating properly from this data.

The UCL survey is based on people self-reporting their actions, and it is likely that more people fail to self-isolate properly for the full amount of time than are willing to admit it. However, there is no evidence to suggest 20,000 people who are sick with Covid fail to self-isolate every day. 

If you test positive for Covid-19 or are told to self-isolate by NHS Test and Trace it is a legal requirement to do so.