Covid-19: how Apple and Google's system could help end lockdowns

Apple and Google are teaming up to fight back against the coronavirus pandemic.

Apple announced on Friday that it will work with Google on a new contact tracing system, designed to shed light on who has made contact with infected patients. By using the smartphones that reside in almost everyone's pockets, the two firms aim to track who came in close enough contact to potentially contract the virus themselves.

"By targeting recommendations to only those at risk, epidemics could be contained without need for mass quarantines"

As coronavirus symptoms can take up to two weeks to surface, this tracing system could alert people that would have otherwise spread the virus around without knowing. It could also act as a finely-tuned means of controlling the virus' spread. University of Oxford research published last month suggested the right contact tracing app could even contain the spread without the need for mass lockdowns.

"A contact-tracing App which builds a memory of proximity contacts and immediately notifies contacts of positive cases can achieve epidemic control if used by enough people," the paper's authors, who come from a mixture of tech and health backgrounds, write. "By targeting recommendations to only those at risk, epidemics could be contained without need for mass quarantines (‘lock-downs’) that are harmful to society."

The large-scale collaboration between the two rival California-based firms, which develop the two largest smartphone operating systems, the open-source Android and the closed-system iOS, highlights how the virus pandemic has reshaped faultlines. Since its rapid spread across the world since the start of this year, the novel coronavirus has pressured governments to make sweeping changes in social and economic policy in a bid to halt the spread. Lockdowns are the norm, fiscally conservative governments have announced greatly expanded social safety nets, and tech firms are now seeking to boost interoperability.

To harken back to an old Apple slogan, the pandemic is pressing global forces to think different, and fast.

What exactly are Apple and Google trying to do?

The two firms are seeking to enable what's called "contact tracing." This involves tracking down who came into contact with a patient. This can involve detective work that makes it seem like a medical version of CSI: asking the right questions, speaking to firms like airlines to work out who sat near a patient, and creating a map of the patient's movements over the past two weeks.

Singapore is one country carrying out contact tracing for the novel coronavirus. The Straits Times has an explainer video on how this works:

What Apple and Google are doing is trying to make this process more straightforward, by using the Bluetooth radios inside practically every modern smartphone to judge who came near any given person.

That could make contact tracing far more effective. A University of Oxford study published in Science last month claimed that the viral spread cannot be controlled by manual contact tracing, but an app could streamline the process. The research claimed it could even end the need for mass lockdowns.

How does it work?

The two firms have released preliminary specifications for the system design.

The system uses the Bluetooth Low Energy specification to track when a user comes into close contact with another user. It does not use GPS or any other location technology, which means it doesn't track a person's location on any sort of map.

There are three identifiers at play here:

• The Tracing Key. This is made when a user signs up for contact tracing and never leaves the phone.
• The Daily Tracing Key. A new key is generated every 24 hours, derived from the Tracing Key.
• The Rolling Proximity Identifier. This is derived from the Daily Tracing Key, every time your Bluetooth MAC address changes. Signal founder Moxie Marlinspike claimed on Twitter that this happens around every 15 minutes.

You've tested positive for Covid-19? The Daily Tracing Keys from the days you might have infected others are uploaded to a server. Other phones download those keys from the server and use them to derive the Rolling Proximity Identifiers. The phones can then look at the list of identifiers they detected and alert a user if they came close to a phone belonging to a patient. Matches are not shared with the server.

So how does it know whether a patient came into close enough contact? Apple told The Verge that it's still trying to work out the finer details, like how long two users need to remain close to trigger an event. The company has suggested a time of five minutes could be enough to trigger. That could solve the time issue, but Bluetooth signals can still travel up to 30 feet – well beyond the six feet of distance required by health authorities.

How will people use Apple and Google's systems?

Apple and Google's plan has two phases. The first phase will arrive in May, and involves launching an application programming interface for both Apple's iOS and Google's Android operating systems. This will allow public health authorities to build apps to use the technology and release them in the respective app marketplaces.

Details are vague, but this would suggest a national government or health authority could build an app that would enable population-wide contact tracing. Imagine a new app launching, complete with a big ad campaign, that authorities encourage everyone download to fight the disease. Similar to "wash your hands" or "stay at home," "get the app" could be a simple-to-remember message aimed at filtering through.

One of the first adopters could be the United Kingdom. BBC News reported Sunday that NHSX, the National Health Service's digital innovation unit, plans to use the Apple and Google system in its own app. NHSX was not aware of the new system when development started, meaning this implementation was decided partway through the project.

The second and more comprehensive phase is set to launch "in the coming months." This will enable "a broader Bluetooth-based contact tracing platform" built right into iOS and Android. This will work on an opt-in basis.

Again, the details are vague at this stage – the announcement promises information will be openly published for analysis – but the language for the second stage suggests the feature will be built into the operating system instead of requiring users to download an app. Think about the difference between making a population visit the App Store and set up an app versus flicking a switch in the "Settings" menu, and it's clear how a built-in feature could lead to more users.

More users mean more data, and that means a better chance of tracking the virus.

Why is this different from other contact tracing systems?

The two firms' proposal is markedly different from that used in China and rolled out in February. This uses QR codes, scanned by a smartphone's camera, to track a person's movements. Users scan a code as they enter a public place like a shopping mall or metro station. People's health profiles are marked with red, yellow or green depending on their risk.

The new system does bear strong similarities to research led by the Massachusetts Institute of Technology, dubbed PACT or Private Automatic Contact Tracing. This research, announced last week, also uses Bluetooth to track phones within range. The researchers claim it only logs phones that were around six feet away and during an extended period of time.

In a statement to Inverse, the PACT team responded to Apple and Google's announcement:

“We are thrilled to see Apple and Google join the work underway to develop contact tracing systems that could help track the spread of Covid-19 while preserving user privacy. In order for a system such as ours to be implemented widely, it is imperative that smartphone manufacturers and designers like Apple and Google are involved so that any contact tracing system could be deployed widely. We look forward to working with them on advancing this imperative effort to help tackle the Covid-19 pandemic.”

The institution has also been working on a solution that also incorporates GPS to create a map of a user's travels to see if they crossed paths, a project called "SafePaths." This app uses PACT as part of its operation.

Singapore has developed its own Bluetooth-based app called TraceTogether.

But perhaps the biggest difference with all of the efforts listed above is it will one day be included with the smartphone's operating system. It's a benefit that could drive mass adoption and make the tool more useful than ever.

What has been the reaction so far?

"Contact tracing apps ignore half the planet by definition"

Experts have been quick to point out that this will not be a silver bullet to fix the pandemic.

Alex Pentland, director of connection science at MIT, told The Telegraph Monday that a Bluetooth-based solution would give a "false sense of precision." The 30-feet range of Bluetooth makes it easy to inadvertently trigger false positives, even from neighbors through walls.

Hal Hodson, Asia Technology Correspondent at The Economist, wrote on Twitter Monday that "contact tracing apps ignore half the planet by definition," highlighting how the seemingly-ubiquitous smartphone isn't as ubiquitous as it needs to be to fight a global pandemic. Statista shows there are 3.5 billion smartphone users worldwide, meaning just half the world has a smartphone.

But while its effectiveness may be questionable, the system could form part of a strategy that finally builds an alternative to mass lockdowns.

"As the cases come down, if social distancing works, we could be in a world where contact tracing could be effective," John Brownstein, chief innovation officer at Boston Children's Hospital, told ABC.

The Inverse analysis

This could be the best chance for smartphone-based contact tracing to work.

While apps like SafePaths and the Singapore project offer potentially useful features, they all suffer from the issue that users need to download an app to make it work. The Straits Times reported on April 1 that just one in six people had downloaded Singapore's TraceTogether app. NHSX predicts that around half the population going outdoors would need to sign up for an automatic contact tracing system to be effective.

Some details will need to be clarified about Apple and Google's system, like how it will avoid false positives and what the second stage of the rollout will look like – including whether users would still need to download an app to fully utilize the service. But even a limited level of integration into the operating system could be a powerful way of encouraging adoption on a large scale, while also ensuring the tools have full access to the necessary information to work to their full potential.