Officials are looking at “tuning” the NHS Covid app to be less sensitive after the number of people “pinged” into isolation soared 62% in a week.
Top government advisor Dr Jenny Harries today revealed more changes could be announced to stop millions being forced to quarantine.
Some 356,036 app users were told to self-isolate due to contact with a Covid case in the week to June 30 – up from 219,391 the week before.
And the total looks set to soar, as double-jabbed contacts will only become exempt from self-isolation on August 16.
Chancellor Rishi Sunak and Downing Street today hinted at further changes to the app before the August 16 change.
Mr Sunak said the government will be looking at “a more proportionate and balanced approach” amid warnings of a tide of absences and ruined holidays.
And Dr Harries, chief of the new UK Health Security Agency, revealed: “We have another piece of active work ongoing at the moment.
“It may be possible to tune the app so it’s appropriate to the risk.”
She added: “As the population becomes more vaccinated, we know there will be an improvement in the reduction of risk of serious illness, hospitalisation and death.
“In that case the move to reduce self isolation will be appropriate.”
She went on: “We’re working through what a vaccination populated app means – that’s something we’re working on at the moment.”
Health Secretary Sajid Javid has already announced double-jabbed Brits will no longer have to self-isolate from August 16 if they come into contact with a positive case.
But by his own admission, there could be 100,000 new Covid cases a day by then.
Almost three people on average are “pinged” by the app for every one person who tests positive. That suggests more than 2million people a week could be told to isolate before August 16 kicks in.
Speaking today, Mr Sunak appeared to suggest more changes could be coming down the track.
He told BBC Breakfast: “I recognise people’s frustrations with this.
“What I can tell you is having spoken to the Health Secretary about it he’s also aware of this.
“We have two different systems for self-isolation – we have the NHS test and trace system where you get called and we also have the app.
“And I think most people’s concerns rest with the app and that does account for the majority of the self-isolation contact cases.
“But what I can tell you is the Health Secretary is aware of the frustrations around this, he’s looking at the difference between those two systems, and seeing what might be a more proportionate and balanced approach to this.”
Unlike the Test and Trace system, the NHS Covid app is able to detect contacts between two people who do not know each other, such as on a bus or train.
However, all its data is anonymised and unlike a phone call from Test and Trace, its ‘pings’ are not a legally-enforceable order to isolate.
Most of England’s remaining lockdown restrictions will end if the Government proceeds with Step 4 on July 19 – meaning cases are expected to soar.
But changes to self-isolation rules will not come in for another four weeks.
That will mean millions of Brits could be exposed to Covid, and still have to follow isolation rules even if they are double-jabbed.
After August 16, fully-vaccinated individuals and under-18s will no longer be told to stay at home if they have come into contact with a coronavirus case.
But they will instead be advised to take a test, and people with confirmed cases of Covid-19 will still be told to self-isolate.
Transport Secretary Grant Shapps is expected to outline similar measures for foreign travel later this morning.
He told Prime Minister Boris Johnson that businesses fear “carnage” with the loss of staff to isolation, and people having to cancel social plans.
Some people have suggested they have deleted the app to avoid isolation requests for contacts with Covid-19 infections.