Ministers are to radically alter the NHS Covid-19 app to slash the number of people instructed to isolate after they are in contact with someone who has tested positive, in the latest move to try to combat the numbers of people in quarantine.
From Monday, the app will instruct contacts to isolate only if they have been close to someone in the two days leading up to a positive test, rather than the current five-day threshold.
The change, which the government said was in line with the latest public health advice, is a significant reversal of No 10 policy, which had said there were no plans to change the way the app operated or tweak its sensitivity. The alert is based on an algorithm that uses Bluetooth to track those who have been within 2 metres of someone with the disease for 15 minutes or more, but also check-in data at venues including bars and restaurants.
It comes amid reports that people are ditching use of the app in droves, and the Department of Health said it was urging people to continue to use the app now the change had been made.
The number of people contacted by the app reached record levels in the week to 21 July, according to the latest data, with more than 685,000 people told to self-isolate.
Yet evidence is growing that the public is making less use of the app – only 6.6m check-ins were recorded in total in the week ending 21 July, a 47% drop compared with the week ending 30 June.
DHSC said the update did not impact the sensitivity of the app, or change the risk threshold, and would result in the same number of high-risk contacts being advised to self-isolate.
The health secretary, Sajid Javid, said: “We want to reduce the disruption that self-isolation can cause for people and businesses, while ensuring we’re protecting those most at risk from this virus. This update to the app will help ensure that we are striking the right balance.
“It’s so important that people isolate when asked to do so in order to stop the spread of the virus and protect their communities.”
The Department of Health and Social Care said the app had prevented thousands of potential infections, despite the outcry over the numbers isolating. Advice is expected to change on 16 August, meaning those who have been fully vaccinated will no longer be required to isolate.
DHSC said the app prevented up to 2,000 cases a day in July and more than 50,000 cases overall, assuming there was 60% compliance with the app, preventing an estimated 1,600 hospital admissions.
Dr Jenny Harries, the chief executive of UK Health Security Agency, said the technology should still be used to fight the virus.
“I strongly encourage everyone, even those fully vaccinated, to continue using the app. It is a lifesaving tool that helps us to stay safe and to protect those closest to us as we return to a more familiar way of life.”