NHS COVID-19 app's first weekend: With fundamental testing flaw ironed out, bugs remaining are relatively trivial

Shaky start out of the gates and still some issues, but at least it's here


England and Wales finally have a contact-tracing app. Released last Thursday, NHS COVID-19 allows public health authorities to identify potential disease carriers and stem the spread of coronavirus. But in the days since its release, some bugs have showed up.

As with major software created under pressing time conditions, NHS COVID-19 faced initial teething pains. One bug, which was eventually resolved by the developers on Sunday, meant users were unable to register a positive test if it was booked outside of the contact-tracing app.

NHS COVID-19 uses confirmatory testing to alert users who have been in contact with someone carrying the disease. In addition to registering and ranking interactions, it allows users to request a test. Results are provided to the patient with an SMS code, which is uploaded to the app.

A vast chunk of COVID-19 testing is performed outside of the app. NHS hospitals and clinics routinely test patients. Public Health England performs its own tests. Separately, the Office of National Statistics is embarking on a wider, untargeted spate of COVID-19 testing in order to surveil the prevalence of the disease in the wider population. These are in addition to testing performed by private healthcare providers.

The inability to register the results of these tests represented a huge blind spot for NHS COVID-19.

NHSX and the Department of Health resolved this myopia. From Sunday, anyone who receives a positive test result administered by another government body will also receive an SMS code allowing them to register the result with the app and warn all their close contacts.

"Everyone who receives a positive test result can now log their result on the app. If you get a test in a NHS hospital, through a PHE lab – which carry out tests for NHS hospitals – or in a surveillance study, you can request a code from NHS Test and Trace to log a positive result," the Department of Health said in a statement yesterday.

However, it is unable to recognise negative test results performed outside of the app.

The Department for Health is keen to tout the swift uptake. The body claims NHS COVID-19 has been downloaded 10 million times since its release last Thursday. Six million of those downloads occurred during the first 24 hours.

Check In, preferably to the right place

Like its (since abandoned) predecessor, NHS COVID-19 is an open-source product and the code is available to view on GitHub. In addition, members of the public can flag problems and perceived bugs through the appropriate issue tracker. The app is divided into several different repositories, each corresponding to a different part of the software ecosystem.

The previous NHS contact-tracing app included several crippling problems as the developers unsuccessfully tried to implement functionality that would later become available through the APIs provided by Google and Apple. In some cases, it proved impossible for phones of differing types to reliably exchange "handshakes" – which is a core component of any contact-tracing application.

This time around, NHS techies haven't been forced to reinvent the wheel so the issue tracker is filled with relatively trivial problems.

Trivial and, in some cases, amusing. For example: the NHS COVID-19 app allows individuals to "check in" to a venue, a bit like they would with Swarm (formerly Foursquare) or Facebook. This is done by scanning a QR code. Venues are obligated by law to display these codes.

To help venues, the respective healthcare services have provided visual templates which they can build upon. The NHS in England has opted to use a dummy QR code. At the bottom of the page is a sample address, which is blurred in order to make it fully illegible.

The QR Code templates in Wales followed the same tack, but neglected to blur the (very real) sample address. The address, which purports to belong to an establishment called "Terry's Welsh Bar", actually belongs to an Indian takeaway in Briton Ferry called Adil Masala.

The person who identified the problem has since created a pull request, which replaces the original poster with a redacted one. It is yet to be accepted. ®


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