The government insists that people who are pinged by the NHS COVID app must self-isolate immediately.
It comes amid confusion over messaging from ministers and the continued “pingdemic”, whereby thousands of people are being told to quarantine as coronavirus cases rise.
Downing Street was forced into an embarrassing position on Monday after one minister suggested people shouldn’t automatically self-isolate after being pinged by the NHS COVID-19 contact tracing app.
Number 10 slapped down his comments, saying it was “crucial” to self-isolate when told and that businesses should be supporting employees to do so.
On Monday, a poll by YouGov revealed that only one in five Britons have the app and are using it correctly.
A third of Britons have had it and abused it, while 40% have never downloaded it, according to the survey of more than 1,700 adults.
Hundreds of thousands of people have been told to stay at home in the pingdemic after the app deemed them to have been in close contact with someone who has tested positive for COVID-19.
More than 500,000 people in England and Wales were notified by the app to self-isolate in the week up to 1 July.
It means many small businesses have been forced to close and larger companies have also been affected – pub chain Greene King shut 33 pubs in the last week and PureGym said up to 25% of staff are isolating in some areas.
However, there is no legal requirement to self-isolate when pinged by the app, as opposed to testing positive for coronavirus or being contacted by NHS Test and Trace.
The self-isolation rules will remain in place until 16 August, after which people who have had both vaccine jabs will not have to quarantine if they have been in contact with someone who has tested positive.
On Monday, junior business minister Paul Scully suggested that self-isolating after being told to do so by the app was a decision for individuals and employers.
But Downing Street was quick to dismiss this.
A Number 10 spokeswoman said: “Isolation remains the most important action people can take to stop the spread of the virus.
“Given the risk of having and spreading the virus when people have been in contact with someone with COVID, it is crucial people isolate when they are told to do so, either by NHS Test and Trace or by the NHS COVID app.”
Boris Johnson has stressed the importance of self-isolation as “one of the only shots we have got left in our locker to stop the chain reaction of the spread of COVID”.
Shadow health minister Justin Madders accused the government of “making it up as they go along”.
The Labour MP said: “Ministers mix messages, change approach and water down proposals when the public and businesses need clarity and certainty.”
Watch: What is the 'pingdemic' and do people alerted by COVID app have to isolate?