One way to track the spread of COVID-19 across a population is through contact tracing. Apple and Google today announced a “joint effort” that leverages Bluetooth on Android and iOS phones to “help governments and health agencies reduce the spread of the virus.”

The two companies are launching a “comprehensive solution” for contract tracing that encompasses “application programming interfaces (APIs) and operating system-level technology to assist in enabling contact tracing.”

This is an alternative to relying on location data approaches from carriers and other telecom companies that some countries have already implemented.

Based on these upcoming tools, governments will be able to build COVID-19 contact tracing apps that work across Apple and Google devices. When two people are in close-range, their phones will exchange anonymous identifiers. If an individual gets diagnosed with COVID-19, they can have their device transmit a list of everybody they’ve been in contact with to the cloud.

Meanwhile, the second person’s phone will periodically download a list of everyone that has tested positive in their area. If a match occurs, they will be notified and prompted to contact health authorities.

These APIs will be available by May, and those “official apps” from public health agencies can be downloaded through Google Play and the App Store.

A second joint effort is focused on creating a “broader Bluetooth-based contact tracing platform by building this functionality into the underlying platforms.” Third-party apps will no longer be required, with contact tracing built into Android and iOS directly. While still requiring manual opt-in, this should increase adoption.

Both companies in their joint press release this morning are heavily focused on the privacy angle. Key points include:

  • Explicit user consent required
  • Doesn’t collect personally identifiable information or user location data
  • List of people you’ve been in contact with never leaves your phone
  • People who test positive are not identified to other users, Google, or Apple
  • Will only be used for contact tracing by public health authorities for COVID-19 pandemic management

Apple and Google today released draft technical documentation about the Bluetooth and cryptography specifications and framework needed for COVID-19 contact tracing:

  • Privacy-safe contact tracing using Bluetooth Low Energy
  • Contact Tracing Bluetooth Specification
  • Contact Tracing Cryptography Specification

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Contact tracing can help slow the spread of COVID-19 and can be done without compromising user privacy. We’re working with @sundarpichai & @Google to help health officials harness Bluetooth technology in a way that also respects transparency & consent. https://t.co/94XlbmaGZV

— Tim Cook (@tim_cook) April 10, 2020

To help public health officials slow the spread of #COVID19, Google & @Apple are working on a contact tracing approach designed with strong controls and protections for user privacy. @tim_cook and I are committed to working together on these efforts.https://t.co/T0j88YBcFu

— Sundar Pichai (@sundarpichai) April 10, 2020