California’s CA Notify app to offer statewide exposure notification using Apple and Google’s framework

The state of California has now expanded access of its CA Notify app to all in the state, after originally deploying the app in a pilot program at UC Berkeley in November, which later expanded to other UC campuses. The statewide launch of the app, announced by California Governor Gavin Newsom on Monday, means that the tool based on Apple and Google’s exposure notification API will be available for download and opt-in use to anyone with a compatible iPhone or Android device as of this Thursday, December 10.

Apple and Google’s jointly-developed exposure notification API uses Bluetooth to determine contact between confirmed COVID-positive individuals and others, alerting users to potential exposure without storing or transmitting any data related to their identity or location. The system uses a randomized, rolling identifier to communicate possible exposure to other devices, and individual state health authorities can customize specific details like how close, and for how long individuals need to be in contact in order to quality as an exposure risk.

In the case of California, the state has set contact with a confirmed COVID-19 positive individual of within 6 feet, for a period of 15 minutes or more as meriting an exposure notification. Users who receive a positive COVID-19 test will get a text message from the Department of Public Health for the state that contains a code they input in the CA Notify app in order to trigger an alert broadcast to any phones that met the criteria above during the prior 14 days (the period during which the virus is transmissible).

As mentioned, there’s no personal information transmitted from a user’s device via the notification system, and it’s a fully opt-in arrangement. Other states have already deployed exposure notification apps based on the Apple/Google API, as have many other countries around the world. It’s not a replacement for a contact tracing system, in which healthcare professionals attempt to determine who a COVID-19 patient came in contact with to find out how they might have contracted the virus, and to whom they may spread it, but it is a valuable component of a comprehensive tracing program that can improve its efficacy and success.