In a rare joint announcement, Apple Inc. and Google LLC today revealed plans to build a decentralized coronavirus tracking system that will enable health authorities to notify people if they come into contact with a COVID-19 patient.

The system will use people’s iOS or Android devices to determine if they’ve been exposed. Anticipating the privacy concerns the project is bound to raise, Apple and Google said they plan to make participation opt-in only and pledged not to collect personally-identifiable data about users or track their location. 

The companies’ statement described the project as “joint effort to enable the use of Bluetooth technology to help governments and health agencies reduce the spread of the virus, with user privacy and security central to the design.”

When users opt in, their handsets start using Bluetooth to broadcast a “key” that can be picked up by other devices connected to the system. Thus, if two individuals who’ve both opted in come near one another, each of their devices will receive the other’s key. These keys are then sent to a server that uses them to confirm those two individuals met.

If one of the two individuals in the hypothetical meeting is diagnosed with COVID-19, that individual can notify local health authorities and the keys from their device will make it possible to find and alert the person with whom they’ve met. That person, in turn, will receive a message informing them that they’ve come into contact with a COVID-19 patient.

The system is slated to roll out in two phases. First, Apple and Google will launch an application programming interface in mid-May that will enable health authorities to build opt-in coronavirus tracking apps. Later on, the companies will release updates for iOS and Android that will integrate the system directly into their respective operating systems so users won’t have to download anything if they choose to participate. 

“All of us at Apple and Google believe there has never been a more important moment to work together to solve one of the world’s most pressing problems,” the companies’ statement read. “Through close cooperation and collaboration with developers, governments and public health providers, we hope to harness the power of technology to help countries around the world slow the spread of COVID-19 and accelerate the return of everyday life.”

Even apart from the privacy concerns, there’s skepticism about how well such a system would work. According to Farzad Mostashari, former national coordinator for health information technology at the Department of Health and Human Services and now chief executive of healthcare technology company Aledade Inc., these contact tracing systems require many people to opt in to be effective, and even then there can be many false positives.

Image: Google