London Daily

Focus on the big picture.
Wednesday, Sep 17, 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
Effective and Impressive Generation Z Protest: Images from the Riots in Nepal
European manufacturers against ban on polluting cars: "The industry may collapse"
Sam Altman sells the 'Wedding Estate' in Hawaii for 49 million dollars
Trump: Cancel quarterly company reports and settle for reporting once every six months
Turkish car manufacturer Togg Enters German Market with 5-Star Electric Sedan and SUV to Challenge European EV Brands
US Launches New Pilot Program to Accelerate eVTOL Air Taxi Deployment
Christian Brueckner Released from German Prison after Serving Unrelated Sentence
World’s Longest Direct Flight China Eastern to Launch 29-Hour Shanghai–Buenos Aires Direct Flight via Auckland in December
New OpenAI Study Finds Majority of ChatGPT Use Is Personal, Not Professional
Hong Kong Industry Group Calls for HK$20 Billion Support Fund to Ease Property Market Stress
Joe Biden’s Post-Presidency Speaking Fees Face Weak Demand amid Corporate Reluctance
Charlie Kirk's murder will break the left's hateful cancel tactics
Kash Patel erupts at ‘buffoon’ Sen. Adam Schiff over Russiagate: ‘You are the biggest fraud’
Homeland Security says Emmy speech ‘fanning the flames of hatred’ after Einbinder’s ‘F— ICE’ remark
Charlie Kirk’s Alleged Assassin Tyler Robinson Faces Death Penalty as Charges Formally Announced
Actor, director, environmentalist Robert Redford dies at 89
The conservative right spreads westward: a huge achievement for 'Alternative for Germany' in local elections
JD Vance Says There Is “No Unity” with Those Who Celebrate Charlie Kirk’s Killing, and he is right!
Trump sues the 'New York Times' for an astronomical sum of 15 billion dollars
Florida Hospital Welcomes Its Largest-Ever Baby: Annan, Nearly Fourteen Pounds at Birth
U.S. and Britain Poised to Finalize Over $10 Billion in High-Tech, Nuclear and Defense Deals During Trump State Visit
China Finds Nvidia Violated Antitrust Laws in Mellanox Deal, Deepens Trade Tensions with US
US Air Force Begins Modifications on Qatar-Donated Jet Amid Plans to Use It as Air Force One
Pope Leo Warns of Societal Crisis Over Mega-CEO Pay, Citing Tesla’s Proposed Trillion-Dollar Package
Poland Green-Lights NATO Deployment in Response to Major Russian Drone Incursion
Elon Musk Retakes Lead as World’s Richest After Brief Ellison Surge
U.S. and China Agree on Framework to Shift TikTok to American Ownership
London Daily Podcast: London Massive Pro Democracy Rally, Musk Support, UK Economic Data and Premier League Results Mark Eventful Weekend
This Week in AI: Meta’s Superintelligence Push, xAI’s Ten Billion-Dollar Raise, Genesis AI’s Robotics Ambitions, Microsoft Restructuring, Amazon’s Million-Robot Milestone, and Google’s AlphaGenome Update
Le Pen Tightens the Pressure on Macron as France Edges Toward Political Breakdown
Musk calls for new UK government at huge pro-democracy rally in London, but Britons have been brainwashed to obey instead of fighting for their human rights
Elon Musk responds to post calling for the murder of Erika Kirk, widow of Charlie Kirk: 'Either we fight back or they will kill us'
Czech Republic signs €1.34 billion contract for Leopard 2A8 main battle tanks with delivery from 2028
USA: Office Depot Employees Refused to Print Poster in Memory of Charlie Kirk – and Were Fired
Proposed U.S. Bill Would Allow Civil Suits Against Judges Who Release Repeat Violent Offenders
Penske Media Sues Google Over “AI Overviews,” Claiming It Uses Journalism Without Consent and Destroys Traffic
Indian Student Engineers Propose “Project REBIRTH” to Protect Aircraft from Crashes Using AI, Airbags and Smart Materials
French Debt Downgrade Piles Pressure on Macron’s New Prime Minister
US and UK Near Tech, Nuclear and Whisky Deals Ahead of Trump Trip
One in Three Europeans Now Uses TikTok, According to the Chinese Tech Giant
Could AI Nursing Robots Help Healthcare Staffing Shortages?
NATO Deploys ‘Eastern Sentry’ After Russian Drones Violate Polish Airspace
Anesthesiologist Left Operation Mid-Surgery to Have Sex with Nurse
Tens of Thousands of Young Chinese Get Up Every Morning and Go to Work Where They Do Nothing
The New Life of Novak Djokovic
The German Owner of Politico Mathias Döpfner Eyes Further U.S. Media Expansion After Axel Springer Restructuring
Suspect Arrested: Utah Man in Custody for Charlie Kirk’s Fatal Shooting
In a politically motivated trial: Bolsonaro Sentenced to 27 Years for Plotting Coup After 2022 Defeat
German police raid AfD lawmaker’s offices in inquiry over Chinese payments
Turkish authorities seize leading broadcaster amid fraud and tax investigation
×