Only four days after it was released nationally, the NHS's Covid-19 contact-tracing app has hit ten million downloads despite a launch rocked by technical glitches and setbacks.
The number of downloads represents about a sixth of the total population of England and Wales. Health secretary Matt Hancock hailed the milestone as a strong start, reflective of an "absolutely fantastic response", and encouraged more residents to download the app.
Like similar apps that launched earlier this year in Northern Ireland and Scotland, the technology taps Bluetooth signals to register encounters between two users. If one user later tests positive for COVID-19, the app automatically warns the people that they have come into close contact with and who may be at risk. An alert triggers a 14-day countdown clock that shows users how long they must remain at home for, and helps them book a test from the NHS.
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Alongside contact tracing, the app also provides a "check-in" feature to make it easier for the hospitality sector to record the contact details of customers and staff. Recording visitors' contact details is now a legal requirement for venues like pubs, restaurants, hairdressers and cinemas.
As part of the NHS Covid-19 app, these businesses can download an official QR code to present to visitors, which will register the location's details on the user's phone. If, during that time, a coronavirus outbreak occurs on the business's premises, the venue ID will be sent to all the devices. If a match is found with a device, a warning will be issued to the user with advice on what to do next.
The government has strongly encouraged businesses using their own QR codes to switch to the NHS app's system. Up to 460,000 QR code posters have now been downloaded and printed by venues, and it was reported that there had been 1.5 million venue check-ins last Saturday.
The contact-tracing part of the app is separate to the venue check-in feature, and the proportion of users that are keeping their Bluetooth on at all times to enable contact tracing is unclear at this point. The Department of Health and Social Care (DHSC) did not reply to ZDNet's request for a clarification at the time of writing.
Despite the app's encouraging debut, many smartphone owners have complained that they couldn't access the technology, as older devices were found to be incompatible with the app. The tool requires phones running iOS 13.5 or Android 6.0 – both of which are not available to phones released before 2015.
Speaking on BBC Breakfast, Hancock maintained that "the vast majority" of smartphone users can use the app. "Only a very small proportion of people have phones that don't have the latest iOS software," said Hancock.
It also emerged that some users were unable to record a positive test result in the app, meaning that they couldn't trigger warnings to the close contacts picked up by their devices.
Test results, whether positive or negative, can be uploaded automatically to the app when the test has been booked directly through the app's platform. Soon after the technology launched, however, users took to social media to point out that if a test was booked separately, results could not be shared in the app.
The health services currently carry out tests through various different routes, with swab testing in PHE labs and NHS hospitals constituting the first pillar of testing. The app, however, only lets users book a free test as part of the second pillar of testing – swab testing for the wider population via private labs such as Lighthouse Lab.
Last Friday, 215,636 tests were carried out in England, with about 61,500 of those supported by PHE labs and NHS hospitals. This means that, if all of the patients who were tested had downloaded the app, about a third of them couldn't have uploaded their results to the platform.
This flaw was rapidly fixed, and the NHS has confirmed that patients who were previously unable to log their test results will now be able to request a code to input on the app. However, they will only be able to do so for positive test results, meaning that users who have reported symptoms but received a negative test result won't be able to stop the self-isolation countdown started by the app.
And experts have stressed a number of other shortcomings. For example, the "check-in" function does not come with a check-out feature; instead, the app will keep users checked in to the same venue until they register somewhere else, or midnight comes, whichever happens first.
Users, therefore, are likely to be checked in to venues for much longer than they have actually spent on the location's premises, and to receive alerts even if they are not at risk. An accumulation of false positives in an already struggling testing system certainly doesn't bode well.