How Covid-19 Contact Tracing Works on Your Phone

How Covid-19 Contact Tracing Works on Your Phone

How Covid-19 Contact Tracing Works on Your Phone 1280 670 PPE Gears Vietnam

Our smartphones are set to play a significant role in helping navigate our way out of the coronavirus pandemic, with countries and companies around the world preparing their own apps as part of a track-and-trace system to keep infection levels low.

Google and Apple don’t work together on much, but they’re working together on this: a set of underlying protocols inside Android and iOS that are able to speak to each other, even while your phone is in your pocket.

The first fruits of these efforts are now live on Android phones and iPhones—here’s how to find these settings on your phone, and what they actually do.

The Track-and-Trace Technology

Photograph: Apple

What Apple and Google have developed isn’t an app in itself—rather it’s an application programming interface (an API), plus some other fundamental technologies, that other apps can plug into. When you load up a website with a Google Maps widget on it, that is using a Google Maps API, and the Covid-19 tracking tools work in the same way.

In other words, Apple and Google have done the groundwork, making sure that health apps can talk to each other across Android and iOS and get access to the features they need. It’s now up to countries (and states) to develop the apps that plug into these foundations and provide the actual front-end interface for users. (If indeed they decide to—some agencies are working on completely bespoke systems of their own.)

A crucial part of this underlying framework is access to Bluetooth signals. Bluetooth is perfect for low-energy wireless transmission that can run in the background of your phone, without draining the battery excessively. (It’s used for wireless headphones, car stereos, and the like.)

In this case, your phone will be logging other phones it comes into contact with, assuming both your device and the others are running a Covid-19 tracking app that’s been fully enabled (which is why public support is going to be so important). These logs don’t include any identifying information about you; they use random numerical ID codes that change frequently and get trashed completely once they’re older than 14 days (the incubation period for Covid-19).

Based on what we know so far, the apps will be able to log the length of time you’ve been in contact with each person (or rather each individual phone), and how far away you were, judging from the strength of the Bluetooth signals. Any contact that’s less risky (such as briefly passing someone on the street) will be ignored.

Finding the Settings

Very few Covid-19 tracking apps are out in the wild yet, but the features that Apple and Google have worked on are now live. Besides the settings that you’ll find in future tracking apps, you can enable or disable “exposure notification” logging at the operating system level as well—it’s a completely opt-in system.

David Nield via Android 

On Android, open Settings, then tap Google and Covid-19 Exposure Notifications. You’ll be met with a wealth of information about how exposure tracking works, plus two settings that won’t be active until you install a compatible app: One to delete all the random IDs that your phone has collected, and one to turn off the feature completely.

If you use iOS, open Settings and select Privacy, Health, and Covid-19 Exposure Logging. Again, you can turn this logging on or off and read some more information about how it works. To get rid of the random IDs that are stored on your phone, tap the Delete Exposure Log option at the bottom.

For these apps to work, you’ll need your phone’s Bluetooth and location tracking features turned on, though your actual physical location isn’t tracked—the apps won’t know where in the world you are or how many times you’ve left the house today. They’ll only know which random IDs your phone has come into contact with.

David Nield via Android 

If you report yourself as positive for Covid-19, the app will send that record of your rotating IDs to a server, which in turn will send them out to other devices using the system. Anyone who has been nearby in the last two weeks will be pinged with an alert. Those people can then take action themselves (getting tested, self-isolating), potentially stopping another line of transmission.

How the Apps Will Work

Photograph: Apple 

At this stage, we don’t know how, exactly, many of the coronavirus tracking apps built on top of the Apple and Google technologies are going to work. Latvia has been one of the first countries out of the gate, but in the US, the decision on development is going to be made state by state. Utah, for example, has decided to ignore the framework Apple and Google have put together in its own tracking app.

Here’s how the apps built on the Google and Apple tech are likely to function: First, you’ll have the choice whether to download an app at all and whether to enable the coronavirus tracking at the mobile OS level, as explained above. If you contract Covid-19, you then have another choice whether to alert the people that you’ve been in close proximity to.

To avoid false positives, there’ll have to be some form of verification—a kind of certification from a health authority that a Covid-19 test has indeed come up positive, to prevent people from pretending or incorrectly entering that they have caught the coronavirus. This could involve a verification code, for example, though this is one of the details to be finalized.

At the other end of the line, if you have been in contact with someone who has caught Covid-19, your phone will let you know. You won’t see the name of the person who’s tested positive—or when or where it happened—only that you’re now at risk and should probably think about getting checked out and limiting your social interactions. No personally identifiable information will be accessible by Apple or Google.

If and when apps launch across the world, all of this should be explained again, with local caveats and tweaks depending on the region and how local health authorities have decided to use the technology. Apple and Google have said that access will be granted only to public health authorities, and that their apps “must meet specific criteria around privacy, security, and data control” to qualify—which is why some countries and states might decide to go their own way.

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