Apple and Google’s engineering teams have banded together to create a decentralized contact tracing tool that will help individuals determine whether they have been exposed to someone with COVID-19.
Contact tracing is a useful tool that helps public health authorities track the spread of the disease and inform the potentially exposed so that they can get tested. It does this by identifying and “following up with” people who have come into contact with a COVID-19-affected person.
The first phase of the project is an API that public health agencies can integrate into their own apps. The next phase is a system-level contact tracing system that will work across iOS and Android devices on an opt-in basis.
The system uses on-board radios on your device to transmit an anonymous ID over short ranges — using Bluetooth beaconing. Servers relay your last 14 days of rotating IDs to other devices, which search for a match. A match is determined based on a threshold of time spent and distance maintained between two devices.
If a match is found with another user that has told the system that they have tested positive, you are notified and can take steps to be tested and to self-quarantine.
Contact tracing is a well-known and debated tool, but one that has been adopted by health authorities and universities that are working on multiple projects like this. One such example is MIT’s efforts to use Bluetooth to create a privacy-conscious contact tracing tool that was inspired by Apple’s Find My system. The companies say that those organizations identified technical hurdles that they were unable to overcome and asked for help.
Our own Jon Evans laid out the need for a broader tracing apparatus a week ago, along with the notion that you’d need buy-in from Apple and Google to make it happen.
The project was started two weeks ago by engineers from both companies. One of the reasons the companies got involved is that there is poor interoperability between systems on various manufacturer’s devices. With contact tracing, every time you fragment a system like this between multiple apps, you limit its effectiveness greatly. You need a massive amount of adoption in one system for contact tracing to work well.
At the same time, you run into technical problems like Bluetooth power suck, privacy concerns about centralized data collection and the sheer effort it takes to get enough people to install the apps to be effective.