The future of digital contact tracing

So far in the show we’ve talked covid testing and monitoring. Now to tracking and tracing the infection. Last week, Germany launched what it claims is the world’s best app for covid contact tracing. We were expecting ours in May, but so far it’s failed to materialise. Last week we got the lowdown on this from University of Strathclyde security engineer Greig Paul...

Greig - They had an app, they were testing it on the Isle of Wight. And it started to hit some teething problems around iOS devices recognising each other. And the reason for this was Apple has some technical restrictions on how Bluetooth works on their devices, that they're not able to work around unless they go down Apple's approved route of contact tracing.

So what’s next? What if the app doesn’t happen? Where does digital contact tracing go from here? Ramsey Farragher is CEO of Cambridge company Focal Point Positioning, who specialise in navigation and positioning. Ramsey joined us on the show back in March with a proposal to use bluetooth for Covid contact tracing, and Chris caught up with him, firstly asking why the UK has struggled so much to get the contact tracing app off the ground...

Ramsey - The challenge that has come about with the UK contact tracing app was fundamentally that this unknown problem occurred, which was to do with the iPhones, basically being asleep when the Bluetooth signal was trying to wake them up. Instead of just turning that bit off, so that that wouldn't happen anymore, Apple and Google got together and created their own view of how contact tracing should be done. It prioritises battery life and it prioritises privacy. And that means they fundamentally change bits to do with how Bluetooth is used. And it does indeed turn out that the NHSX app was doing a better job of determining how close another device was than the Google and Apple system can do. And it's because of these priorities. And so people like me are sort of advising Apple and Google and others on changes they can make to make it a bit better. The simplest thing is to do with how often the devices try to talk to each other.

Chris - If I may, why do we have to use Bluetooth? This is a radio wave, isn't it, between two devices. And I put it to you that if you're sitting on one side of wall and I'm sitting on the other and Bluetooth goes through the wall, the device doesn't necessarily know there's a wall there, because radio sees a wall as transparent and goes straight through. Why can't we use some other way? Why can't we do it with sound for example, it's perfectly capable of making, we can make a dog whistle that my dog can hear and probably my children, but I can't. Why can't we make the phones, do this with sound?

Ramsey - We can, and people are starting to look into ultrasound for this. The reason we started with Bluetooth is because it's all set up already in the phone for them to talk to each other over Bluetooth. And you're right, the signal goes through walls and windows and glass, and that means you'll get more false positives. And so there are entities that are looking at building apps, using ultrasound instead, which at the moment is a bit of a hack. So it's using the speaker and the microphone in your phone to transmit an ultrasonic chirp that you won't hear, but the phones can pick up, and you can use that to detect the proximity of two phones to within a centimetre, which is much better than Bluetooth, which is about a metre in resolution.

Chris - That sounds quite promising. In Singapore, where they're conscious of the fact that not everybody has got a smartphone device, so not everyone's going to want to run one of these things, and there are these headaches with how Apple have decided to inflict themselves on the world, people are using other kinds of specialist devices. They've actually issued handheld contact tracing devices that do what they do want to do, without the constraints imposed by third parties. Do you think that might be a possible solution here?

Ramsey - Yeah, it's a really good idea. It gets around the challenges that we've seen with trying to do it directly on smartphones. And it means that vulnerable people who might not have a smartphone or might not remember to keep them charged, can be given a necklace or a bracelet that does the same job and does it with a very long battery life. Because it's dedicated for that role. So they're a good idea. And I think we'll see them over here.

Chris - Do you think that's going to be what we end up doing then? Or do you think we are going to get this mysterious app. Because Germany have done it. They reckon they've got the world's best app. They've got a problem with people wanting not to download it, but that's a different problem.

Ramsey - Well, independent tests of their apps suggest it's not quite as good as they're claiming, but I do know that the Apple/Google methodology is steadily improving, so it will get better and we'll get there in the end. And people like me are trying to make everyone get there as fast as we can.