Pingdemic: How each of the UK's Covid-19 apps work and the differences between them, explained

As the NHS contact tracing app for England and Wales ‘pings’ over 600,000 people in the two UK nations, here’s what you need to know about the different contact tracing Covid apps used across all four nations of the UK and how they work.

Pingdemic: How each of the UK's Covid-19 apps work and the differences between them, explained (Image credit: Getty/PA/HSC Northern Ireland)

With cases beginning to climb once more following the lifting of all legal coronavirus restrictions in England, and further easing of restrictions in Wales, Scotland and Northern Ireland, there has been a perhaps unsurprising surge of ‘pings’ from various Covid-19 apps asking Brits to self-isolate.

This took hold just days after the Prime Minister Boris Johnson declared ‘Freedom Day’ for England on Monday July 19 – as Mr Johnson and Chancellor Rishi Sunak had to self-isolate following Health Secretary Sajid Javid’s receipt of a positive test result.

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Since then tens of thousands of citizens are now self-isolating after rules around face masks, social distancing and limits on numbers of people gathering indoors were removed.

In Scotland, First Minister Nicola Sturgeon has faced scrutiny over Scotland’s Test and Protect contact tracing system as it was said that 10,007 people in the country had been pinged by the Protect Scotland app so far.

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As the spread of the Delta variant continues to see a proliferation in positive coronavirus cases across the UK, here’s what you need to know about each of the UK’s contact tracing apps and how they work.

What are the different UK Covid-19 apps?

It is important to remember that with all four nations adopting their own localised policies and systems to deal with the pressures of the pandemic. Each nation has its own rules and some have different Covid apps too.

While those in England and Wales will be using the NHS Covid-19 App, people living in Scotland will be using the Protect Scotland app and those in Northern Ireland use the StopCOVID NI app.

Each of the apps have the same goal, which is to track and trace positive coronavirus cases and their close contacts in order to keep Covid levels low across all four nations.

But they each have a completely different interface and processes that come with them – with the NHS COVID-19 app in England and Wales operating rather differently to their Scottish and Northern Irish counterparts.

What makes each app different?

All three apps use Bluetooth to exchange encrypted, random and anonymous codes with nearby users of the app in order to detect when someone has been in close contact – usually within two metres of someone for a prolonged period of time – who has tested positive for Covid-19.

The apps will then alert this close contact to let them know that they have been identified as such, meaning they could be at risk of having coronavirus, and will ask them to get tested and self-isolate for 10 days.

This is not a legal requirement, but one that those alerted are strongly advised to take note of and abide in order to reduce any risk of spreading the virus further in local communities.

While the NHS COVID-19 app used in England and Wales has been built by the UK Government using the application programming interface (API) and exposure notifications technology created by Apple and Google (used by all European contact tracing apps including Scotland and Northern Ireland’s), the Protect Scotland and StopCOVID NI apps have been developed fully by US firm NearForm and built on Open Source code initially developed by the Irish government.

Unlike the NHS app for England and Wales, the Scottish app uses a different proximity system to identify close contacts, with a more straightforward approach of exchanging anonymous codes between two users who have been in close contact for 15 minutes or longer.

When a phone owner then tests positive for Covid-19, they receive a unique code inviting them to share their anonymised app data – with other app users who have logged the device’s keys then receiving an exposure notification and being contacted by a contact tracer from NHS Scotland Test and Protect.

The open source software by Irish firm, NearForm, has been used to build similar contact tracing apps worldwide, such as those for Ireland, Gibraltar and US states like Pennsylvania.

The NHS COVID-19 app used in England and Wales also allows users to ‘check in’ to public places they visit, such as bars and restaurants, by scanning QR codes and logging visited locations in the app.

Regardless of their differences, the most important thing to bear in mind across all three apps is that they are all decentralised – meaning that your personal information and location data is not collected, tracked or shared, and any app data collected is completely anonymised.

How many people have been pinged so far for each app?

According to recent statistics, roughly 50,000 people in Scotland have been contacted through Scotland’s app since its launch last year – a figure which contrasts heavily with the more than 500,000 people a week being alerted by England and Wales’ app.

The NHS COVID-19 app most recently saw a huge spike in alerts just last week, with 618,903 people pinged to self-isolate in the week ending July 14.

This accounts for 15.4% of all alerts sent to date, as of its launch in September last year, constituting a record high for the app.

There have been roughly 3.94 million alerts sent from the NHS COVID-19 app so far.

The lower figure for the Protect Scotland app has prompted criticism from opposition MPs and critics, who have said that the lower numbers for Scotland are a sign the app and the nation’s contact tracing strategy is not working as effectively as it could be.

Accusations the Scottish Government deny, declaring Scotland's contact racing app presents the same sensitivity as the English version despite fewer 'pings'

In Northern Ireland, similar ‘pingdemic’ levels have raised fear among business representatives of the potential for further lockdowns to be reimposed to curb the spread, with 1099 positive cases reported in the last 24 hours as of July 22.

How effective are they?

There’s no doubt that using the national Covid-19 app wherever you are is a really helpful way to bolster contact tracing efforts, which are under pressure in the current ‘pingdemic’ as easing restrictions give way to a new spike in cases across the country.

Criticisms are beginning to appear of these apps and how functional they are – with Scotland’s Deputy Chief Medical Officer, Dr Nicola Steedman, recently noting that the Scottish app does not not use the same “complex algorithm” as the NHS COVID-19 app but stressed that the differences in proximity calculations between the two apps “is not to say that ours is less sensitive”.

Readers in England and Wales should also note that from August 16, NHS COVID-19 app users will no longer have to self-isolate when asked to do so by the app but for now, the UK Government continues to stress that users ‘pinged’ by the app to self-isolate should adhere to its recommendations.

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