If you’ve had a cursory glance at your emails, you may have noticed promotions from the university encouraging you to download the StopCOVID NI app. It’s the Northern Ireland contact tracing app and has been presented as a tool to help reduce the spread of COVID-19 on campus. But how does it actually work?

In April 2020, Apple and Google, two of the biggest technology companies in the world, announced that they were working together on an Exposure Notification API. This is a system for health authorities around the world to enable people to be notified if they were in contact with someone who was COVID positive.

Over the summer, several countries began developing their apps, and in July 2020 Northern Ireland was the first part of the UK to launch a contact tracing app.

This means your phone communicates with other phones which also have the relevant app installed. It will exchange a random key if the two devices are two meters of each other for fifteen minutes or more. If one of those people later tests positive for COVID-19, they are given a code by their health authority to enter in the app, which allows the codes collected in the time a person can infect other people (but before symptoms appear) to be uploaded to a server.

Devices regularly check the server, and if they see a code they recognise, this triggers an alert asking the user to self-isolate. In theory, it is a much faster way than manual contact tracing to notify people that they should self-isolate and can inform people on a bus or train that you would not have contact details for. The random keys used mean there is no way for you to be identified at any stage (if you’re concerned about your privacy, I would suggest your social media apps are worse).

But how effective is the system?

Oxford University research has suggested that even lower levels of uptake can still have an effect and help reduce the reproduction rate of the virus. However, the privacy preservation of the system means it is hard to say how many people have been notified to self-isolate. These systems have been brought into use in an incredibly short period of time, so the software developers are learning along with us.

The Bluetooth technology that underpins the whole system was never designed for estimating distance and has had issues in metallic bodies such as trains, where signals are bounced off the carriage walls as was shown by a study performed by Trinity College Dublin. There is also the issue of buy in from the public. Google and Apple collectively have approximately 99% of the smartphone market, but convincing people to download an app is more of a challenge. As well as this, there is a lower rates of smartphone use in older demographics who are most at risk of COVID-19.

Despite the bleak picture, there are ways around some of these problems. The Alan Turing Institute have tried to make better distance judgements with Bluetooth data, while other technology such as ultra-Wideband (UWB) could be a more accurate tool for the job in the future if its adoption rate is high enough.

Do do I think the app is worth having?

Yes. I am an inherent tech optimist and I think the downsides to the end user are pretty minimal, with the potential upside of helping to reduce the spread of a pandemic. Count me in.

Kurtis Bell is an Aerospace Engineering Student at QUB, with a keen interest in tech.

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