London Daily

Focus on the big picture.
Thursday, Sep 11, 2025

It’s right to tweak the NHS Covid app – if only to keep people using it

It’s right to tweak the NHS Covid app – if only to keep people using it

Analysis: the plan to turn down the app’s sensitivity to reduce the number of alerts it sends out makes sense

Turning down the sensitivity of the NHS Covid-19 app is ostensibly an odd proposal to fix the problem of the system telling growing numbers of people to self-isolate.

It sounds, as Keir Starmer has suggested, akin to taking the batteries out of your smoke detector because you are being kept awake by its beeping. You might solve the immediate problem, but if you do not deal with the underlying cause then you are going to have a nasty awakening.

In the week ending 30 June, more than 350,000 people in England were told by the app to self-isolate, meaning well over 10% of the alerts sent out in the history of the app were sent in those seven days. The data for the week ending 7 July will almost certainly show an increase again.

And the figures are up despite compelling evidence that use of the Covid-19 app is down. Check-ins with the app peaked in the week ending 2 June at 14.5m. Since then they have fallen to about 12.5m, which supports anecdotal reports that the number of self-isolation alerts has prompted some people to stop using the app entirely.

But the proposed solution is not necessarily as bad as it looks. The ultimate objective is not, after all, to maximise the number of alerts sent but to save lives by minimising onward exposure while trying not to force people to self-isolate unnecessarily.


The sensitivity of the app is just one aspect of that goal, and it is not something that has been set in stone until now. In November the app’s “risk threshold” was massively increased after it became clear it had launched with a bug that prevented some alerts from being sent. It was increased again in December as England and Wales went into a tier 4 lockdown, public records show.

The app can never be perfect. It relies on the strength of a Bluetooth signal to guess at the distance between two users, and despite months of testing, fundamental problems remain. Is the signal weak because the person is far away or simply because their phone is in their back pocket and they are sitting on it? Is it strong because they are right next to you or because they are on the other side of a window from you?

The threshold is a trade-off: too high and many users will be told to self-isolate unnecessarily; too low and people who might be harbouring Covid-19 will not be warned.

But it is not the only trade-off faced by NHSX, the government unit responsible for digital transformation in health. Another is about getting people to use the app at all. A user deciding to uninstall the app because they are worried it will send false alarms is doubly harmful: not only does that user miss out on the ability to receive alerts, they also lose the ability to warn others if they have had a positive test.

Metcalfe’s law – one of the foundations of the modern world – states that the value of a network is proportional to the square of the number of users. It is the law that makes Facebook an all-powerful titan of tech, and it is the reason why keeping the Covid app installed and activated on the phones of Britons across the country is worth reducing the number of alerts it sends out.

Because, ultimately, the app does work. A study published in Nature earlier this year found that in just over three months to the end of December, the app had averted between 100,000 and 900,000 cases, probably saving thousands of lives in the process.

Newsletter

Related Articles

0:00
0:00
Close
ChatGPT CEO signals policy to alert authorities over suicidal youth after teen’s death
The British legal mafia hit back: Banksy mural of judge beating protester is scrubbed from London court
Surpassing Musk: Larry Ellison becomes the richest man in the world
Embarrassment for Starmer: He fired the ambassador photographed on Epstein’s 'pedophile island'
Manhunt after 'skilled sniper' shot Charlie Kirk. Footage: Suspect running on rooftop during panic
Effective Protest Results: Nepal’s Prime Minister Resigns as Youth-Led Unrest Shakes the Nation
Qatari prime minister says Netanyahu ‘killed any hope’ for Israeli hostages
King Charles and Prince Harry Share First In-Person Moment in 19 Months
Starmer Establishes Economic ‘Budget Board’ to Centralise Policy and Rebuild Business Trust
France Erupts in Mass ‘Block Everything’ Protests on New PM’s First Day
Poland Shoots Down Russian Drones in Airspace Violation During Ukraine Attack
Brazilian police say ex-President Bolsonaro had planned to flee to Argentina seeking asylum
Trinidad Leader Applauds U.S. Naval Strike and Advocates Forceful Action Against Traffickers
Kim Jong Un Oversees Final Test of New High-Thrust Solid-Fuel Rocket Engine
Apple Introduces Ultra-Thin iPhone Air, Enhanced 17 Series and New Health-Focused Wearables
Macron Appoints Sébastien Lecornu as Prime Minister Amid Budget Crisis and Political Turmoil
Supreme Court temporarily allows Trump to pause billions in foreign aid
Charlie Sheen says his father, Martin Sheen, turned him in to the police: 'The greatest betrayal possible'
Vatican hosts first Catholic LGBTQ pilgrimage
Apple Unveils iPhone 17 Series, iPhone Air, Apple Watch 11 and More at 'Awe Dropping' Event
Pig Heads Left Outside Multiple Paris Mosques in Outrage-Inducing Acts
Nvidia’s ‘Wow’ Factor Is Fading. The AI chip giant used to beat Wall Street expectations for earnings by a substantial margin. That trajectory is coming down to earth.
France joins Eurozone’s ‘periphery’ as turmoil deepens, say investors
On the Anniversary of Queen Elizabeth’s Death: Prince Harry Returns to Britain
France Faces New Political Crisis, again, as Prime Minister Bayrou Pushed Out
Murdoch Family Finalises $3.3 Billion Succession Pact, Ensuring Eldest Son’s Leadership
Big Oil Slashes Jobs and Investments Amid Prolonged Low Crude Prices
Court Staff Cover Up Banksy Image of Judge Beating a Protester
Social Media Access Curtailed in Turkey After CHP Calls for Rallies Following Police Blockade of Istanbul Headquarters
Nayib Bukele Points Out Belgian Hypocrisy as Brussels Considers Sending Army into the Streets
Elon Musk Poised to Become First Trillionaire Under Ambitious Tesla Pay Plan
France, at an Impasse, Heads Toward Another Government Collapse
Burning the Minister’s House Helped Protesters to Win Justice: Prabowo Fires Finance Minister in Wake of Indonesia Protests
Brazil Braces for Fallout from Bolsonaro Trial by corrupted judge
The Country That Got Too Rich? Public Spending Dominates Norway Election
Nearly 40 Years Later: Nike Changes the Legendary Slogan Just Do It
Generations Born After 1939 Unlikely to Reach Age One Hundred, New Study Finds
End to a four-year manhunt in New Zealand: the father who abducted his children to the forests was killed, the three siblings were found
Germany Suspends Debt Rules, Funnels €500 Billion Toward Military and Proxy War Strategy
EU Prepares for War
BMW Eyes Growth in China with New All‑Electric Neue Klasse Lineup
Trump Threatens Retaliatory Tariffs After EU Imposes €2.95 Billion Fine on Google
Tesla Board Proposes Unprecedented One-Trillion-Dollar Performance Package for Elon Musk
US Justice Department Launches Criminal Mortgage-Fraud Probe into Federal Reserve Governor Lisa Cook
Escalating Drug Trafficking and Violence in Latin America: A Growing Crisis
US and Taiwanese Defence Officials Held Secret Talks in Alaska
Report: Secret SEAL Team 6 Mission in North Korea Ordered by Trump in 2019 Ended in Failure
Gold Could Reach Nearly $5,000 if Fed Independence Is Undermined, Goldman Sachs Warns
Uruguay, Colombia and Paraguay Secure Places at 2026 World Cup
Florida Murder Case: The Adelson Family, the Killing of Dan Markel, and the Trial of Donna Adelson
×