Why Google and Apple’s Contact Tracing System Just Might Work

the netherlands extends coronavirus lockdown

  • Google and Apple released a public exposure notification API on Wednesday, meant to help health authorities develop their own contact tracing apps to fight the COVID-19 (coronavirus) pandemic.
  • Already, many states and 22 countries across five continents have requested access to the API for their own apps.
  • In part, the idea is to cut down on the overwhelming number of contact tracing apps so that there is a more centralized system.

Today, Google and Apple revealed the first publicly available version of their “exposure notifications system,” meant to augment manual contact tracing procedures—which draw heavily on public health resources—and digital contact tracing apps that use Bluetooth. Contact tracing is a method for tracking whether a person has crossed paths with an individual that has tested positive for COVID-19.


To be clear, Google and Apple’s technology is an API that third party companies affiliated with a public health authority or government can use to roll out their own contact tracing apps that are more uniform across regions, states, and countries. Google and Apple are not releasing an app of their own. The apps their API will enable, though, can push out notifications to individuals’ phones to let them know if they’ve potentially been exposed to the virus.


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“Exposure Notification has the specific goal of rapid notification, which is especially important to slowing the spread of the disease with a virus that can be spread asymptomatically,” Google and Apple told reporters in a briefing on Wednesday afternoon. But to do that, the world needs to come to a consensus, rather than rely on the existing messy web of contact tracing apps in development—and the new API is a step in that direction.


Google and Apple’s contact tracing API exists in a pretty noisy space, with apps in development in academia, like at MIT, and some more extreme efforts at the government level, such as the mandatory Ehteraz app that Qatar is forcing citizens to download. In North Dakota, there are even two apps in development at once. The hope is that Google and Apple’s system will help centralize digital contact tracing and cut back on some of this overlap.

These kinds of apps work by using Bluetooth “chirps” that keep a record of whether or not your phone has come into contact with another Bluetooth device. If a person reports that they’ve tested positive for COVID-19, the associated chirp will let others know that they may have crossed paths with the virus.

a graphic depicting how a contact tracing app works

Public health authorities and governments have asked for their help in that endeavor, presumably because they control most smartphones’ operating systems. Without this partnership, Google and Apple claim that iPhones and Android devices would likely have trouble detecting one another, for example.

The companies say that in most cases, the API will only be available for one app per country to avoid fragmentation, but some exceptions will be made. Presumably, the U.S. is one such instance, since multiple states have requested the API. Another 22 countries across five continents have also requested access.

For these apps to meaningfully quell the spread of COVID-19, it’s pivotal to achieve a high rate of user adoption so that people with the virus can quickly seek medical treatment or at least self-quarantine. After 24 consultations with public health officials, app developers, and epidemiologists, the companies have built in additional privacy protocols to encourage people to trust the system.

singapore health virus
Government Technology Agency (GovTech) staff demonstrate Singapore’s new contact-tracing smartphone app called TraceTogether, as a preventive measure against COVID-19 in Singapore on March 20, 2020. The mobile app uses Bluetooth technology developed by GovTech, in collaboration with the Ministry of Health, to inform users who have had close contact with confirmed coronavirus cases.


“User adoption is key to success and we believe that these strong privacy protections are also the best way to encourage use of these apps,” the companies said.

Once a user has downloaded an app that uses Google and Apple’s underlying API, the individual must explicitly choose to turn on exposure notifications, and may turn the feature off at any point. The API prohibits GPS services, even if a user reports that they’ve tested positive for COVID-19—the tracking only occurs through Bluetooth signals that are not tied to location.


Even then, users have the option to report whether or not they’ve tested positive, it’s up to their discretion. Perhaps most significantly, all metadata associated with the Bluetooth tracking is encrypted, making it difficult to tie any information to a particular person.

Additionally, Google and Apple will not collect information tied to user identity. Only public health authorities can use the exposure notifications, and the companies will not monetize any of these apps.

As the need for exposure notification begins to decline, in tandem with fewer reported cases of COVID-19, Google and Apple will disable the feature on a regional basis. The companies will update the API as they receive feedback. Still, only time will tell if the API becomes a universal model for contact tracing apps.

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