Contact tracing is a crucial part of the Covid-19 puzzle and technology might prove essential to scaling up New Zealand’s tracing capacity, Marc Daalder reports

With the lockdown reducing physical contact between members of the public and testing ramping up, the only missing piece of the Covid-19 puzzle is contact tracing.

Ayesha Verrall, a senior lecturer at Otago University who specialises in infectious diseases, told Newsroom that “nationally, I think we need to be able to trace over a thousand cases’ contacts a day. That’s a lot – any one day, we currently trace 70 or so cases a day.”

That’s a massive gap and there’s no sign so far that the Government is willing or able to increase by a factor of ten the number of people working full-time on contact tracing. This is where technology comes in, Verrall says.

“Using the traditional methods, every case can take a team of nurses – say five – two or three days to trace. That’s current practice in New Zealand – that was just before the lockdown. Most of the cases were coming back from overseas, they had taken domestic flights. You had to call all of the people on the flights, the people who took them in the taxi after the flight and anyone they had mixed with at local shops – it’s just painstaking.”

“We have a limit on our actual, on-the-ground contact tracing workforce, so it’s either going to be call centre-based or a digital solution. Even if we can take 10 percent of the work away from nurses or a call centre, that would be valuable.”

Different options for a solution

What that digital solution would look like is still up for debate. A wide range of strategies have been tried overseas, from Israel using terrorist-tracking programmes to log and notify the contacts of confirmed cases without their consent to a voluntary app in Singapore which relies on Bluetooth to record who a given user has been in close proximity with.

There are two overarching questions at the root of this quest for a solution: Should it be voluntary and should it track people’s contacts or their location?

An involuntary solution, such as that implemented by Israel, naturally comes with privacy and human rights concerns. Theoretically, the Government could go to telcos and demand the location data of a given person who has subsequently tested positive for Covid-19.

When asked by the New Zealand Herald whether the Ministry of Health could ask a telco to hand over the location data of an infected person, Privacy Commissioner John Edwards effectively said that would be permitted. “That could be done under existing law – although the telcos might want some additional assurance that they would not be liable for providing that information,” he told the Herald.

“Under the Privacy Act and Telecommunications Information Privacy Code, telcos are able to disclose telecommunications information where they believe on reasonable grounds that it is necessary to prevent or lessen a serious threat to public health. It is possible that they could also approach me for a special authority under the Privacy Act if they felt one was needed in the circumstances.”

A voluntary system, meanwhile, comes with its own troubles. In particular, asking people to opt-in to a tracking scheme or download a particular app may result in lower levels of compliance than a mandatory scheme that operates without users’ consent.

Where they were or who they were with

The second question, on tracking people’s contacts or their locations, is also crucial the success of any potential solution, says Andrew Chen, a Research Fellow at the University of Auckland’s Koi Tū – the Centre for Informed Futures.

“All of the solutions have their own strengths and weaknesses,” Chen said. “We can talk about, at the small scale, somebody’s been to a bakery and you have to figure out who are all the other customers who have been to that bakery that day. That’s quite hard to do based on location alone.”

“Similarly, if someone goes to Womad or a Tool concert, there’s hundreds of other people there. Cool, you know that the person was there but you have no idea who else was there. What we’ve seen from Singapore and also the European Union is this concept that who you have been with is more important than where you have been.”

Verrall agreed that knowing who someone has been with is more valuable. “That seems much more promising than seeing GPS data on where someone has been because that’s very inaccurate. Even when you call an Uber, you can see your GPS thinks you’re in one place when you’re really 50 metres away,” she said.

Location data could be useful, but not for contact tracing, Chen said. “I think that that can be helpful in trying to answer a different question which is: Are people physical distancing? You can answer that question in a more anonymous way so you can see that there’s a crowd of people sitting on the beach and the police should probably go and tell them to go home.”

“But for the purposes of contact tracing, you would need to know who they are, you would need to have their phone numbers and you’d have to be able to infringe on the peoples’ privacy in that sense, because that’s the only way to make the contact tracing work.”

A Singapore solution for New Zealand?

Both Verrall and Chen have latched onto the model Singapore is using as the most promising solution. Singapore’s official app, called TraceTogether, uses Bluetooth to log when other app users are nearby for a certain amount of time. If a user then tests positive for Covid-19, all of their contacts are notified and told to go into self-isolation for 14 days – but without the original infected person’s identity being compromised.

“I’m not a technologist but it did seem like the Bluetooth option was the most helpful because it generates a list of people who you’ve been within close proximity to during the infectious period,” Verrall said.

“The gating factor for me, that I don’t have the answer to, is what percentage coverage of the population do you need? Is it 100 percent or is it 20 to 30 percent? If we can get away with having, say, 30, 40, or 50 percent, then my preference is to say, let’s have an app that is installed at an individual level that uses Bluetooth to track contacts rather than location,” Chen said.

“That’s an opt-in system, it preserves their privacy because the data is stored on the device, the data is only communicated to the Ministry of Health if someone is sick, and you still get the effect of being able to do that contact tracing very rapidly and quickly by just pushing that signal out through the system.”

Verrall confirmed that a solution doesn’t need to have total coverage and would always be supplemented with manual contact tracing. “If you look at the modelling and international evidence, it is clear that your contact tracing does not have to be perfect. But there are some broad parameters we need to get right: We need to be getting about 80 percent of contacts and we need to be getting them within four days or perhaps less of the time they were infected.

“It’s not the end of the world if we don’t get everyone, but being able to do this at scale, and fast, is really the trick. That’s why I see technology and call centres as being so important in the overall solution. It would be fantastic if we had a solid amount of contacts traced through the app, like 25 to 50 percent – wouldn’t that be fabulous? But that would, I understand, need quite high levels of uptake,” she said.

That uptake is the key question with any voluntary solution like an app. In Singapore, TraceTogether has only been downloaded by about 16 percent of population, which means just 2.6 percent of physical contacts are being traced.

“In order for TraceTogether to be effective, we need something like three-quarters – if not everyone – of the population to have it. Then we can really use that as an effective contact tracing tool,” Singapore’s National Development Minister Lawrence Wong told the Straits Times.

Government action needed

But Verrall is hopeful that an app announced in the near future would see higher levels of uptake in New Zealand because people broadly support the Government’s actions so far. “If the Government could implement this at this time, where there seems to be high trust and support for all these measures, then that would be really positive,” she said. 

Whether the Government will move forward with the speed needed is the next question. Tom Barraclough, a public policy and technology expert at the Brainbox Institute, has been working to generate discussion of the options – and their privacy implications – within civil society, but has also been hoping for Government interest, which he hasn’t yet seen.

“I haven’t seen momentum,” he told Newsroom. “Given that we’ve been working across very short time frames, there’s been a lot of interest in it and I think the media’s been doing a fantastic job at accelerating consideration of what we’re going to do. But what I’m looking for is a clear point of central leadership around which everybody else who has an interest in this area can sort of coordinate.”

“At the moment I think there is just uncertainty about whether we’re going to do this and what it’s going to look like and who gets to make the decision.”

Verrall says the Government needs to be the one to make that decision, or else any voluntary programme won’t have the necessary buy-in.

“There’s a decision to be made about the ambition we’re going to show to get there,” she said.

“I essentially see Government’s leadership on this as crucial to its success. I’m getting 20 messages a day from people who can design apps and that’s great that there’s that sort of talent and enthusiasm and commitment out there, but unless the Government leads it, it’s not going to get the type of buy-in to make it a success.”

Marc Daalder is a senior political reporter based in Wellington who covers climate change, health, energy and violent extremism. Twitter/Bluesky: @marcdaalder

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