Sajid Javid is looking at reducing the sensitivity of the NHS Covid-19 app amid fears that too many people are being unnecessarily pinged and forced to self-isolate. 

The Health Secretary is considering a more "appropriate, balanced and proportionate" approach amid a backlash over the extension of self-isolation rules for the double vaccinated until August 16.

It comes after Rishi Sunak, the Chancellor, said he had spoken to Mr Javid about the app, adding that he was aware of the public’s "frustration" with the system.

Mr Javid has asked officials to examine the sensitivity of the app, which works by using mobile bluetooth technology to identify people’s close contacts. If they later notify the test and trace technology that they have tested positive for Covid, it will advise those contacts to self-isolate for 10 days. 

Whereas manual contact tracing relies on someone identifying their close contacts to test and trace teams, the app is indiscriminate. It uses an algorithm to identify close contacts, who are supposed to have been within two metres of someone with the virus for 15 minutes or more. 

However, critics believe it is too sensitive and fails to make any distinction between indoor and safer outdoor settings. The current figures suggest three people are pinged by the app for every positive case. 

The explosion in exposure notifications has prompted calls from business and NHS leaders for the August 16 lifting to be brought forward amid fears that it is exacerbating staff shortages. 

Self isolation extension poll

Whitehall sources have confirmed that officials are examining whether the app could be changed so that people have to be in closer proximity to an infected person for longer in order to be pinged. 

Speaking to the Commons public accounts committee, Dr Jenny Harries, the head of the UK Health Security Agency, confirmed that work was being done to "tune" the app to ensure that it was there "for a purpose, not for annoyance".

"We have a piece of work ongoing at the moment because it is entirely possible to tune the app to ensure that it is appropriate to the risk," said Dr Harries. 

"When the app came into action, we know it has been hugely successful, but it has been utilised in a world where we did not have vaccinations. So working through what a vaccinated population using the app means is something that we are actively doing at the moment."

It came as new figures showed that the number of  exposure alerts sent to users of the app in England has risen by more than 60 per cent. A total of 356,036 alerts were sent to users in England in the week to June 30 – up from 219,391 the week before. 

While approximately 26 million people have downloaded the app, test and trace data suggests people may increasingly be switching it off to avoid being pinged. Although 14.5 million people used it to check in to venues in the first week of June, that dropped to 12.4 million by the week ending June 23.

Hospitality leaders have warned that as many as a third of workers are either being forced to self-isolate or unable to work due to venues closing, and that some pubs and restaurants may begin telling employees to switch off the app. 

The Telegraph also revealed that NHS staff are deleting the app, with hospital leaders calling for doctors and nurses to be exempted from self-isolation rules before the August 16 lifting. 

Richard Walker, the boss of the supermarket chain Iceland, has described the system as a "s—show", while scientists are warning that members of the public will begin deleting the app to avoid self-isolation. 

Mr Sunak said he had spoken to Mr Javid about the "frustration" that people have with the system. It is understood the Treasury is concerned about the prospect of millions of people being forced to self-isolate in the coming weeks as Covid cases surge and the impact this could have on the economic recovery. 

Mr Sunak told Sky News: "I know most people’s concerns rest with how the app is working, and the Health Secretary is aware of that. The app counts for the majority of the people who need to isolate, I understand, on the numbers, and he’s looking at what the most appropriate, balanced and proportionate approach to isolation is in these circumstances."