CA Notify App: California's Exposure Notification System

California has broadened the availability of its CA Notify application to all residents throughout the state. Initially, the app was introduced as a trial program at UC Berkeley last November, and subsequently extended to additional University of California campuses. California Governor Gavin Newsom announced the statewide release of the application on Monday, making the tool – which leverages Apple and Google’s exposure notification API – accessible for download and voluntary use to any individual possessing a compatible iPhone or Android device starting this Thursday, December 10.

The exposure notification API, a collaborative effort from Apple and Google, utilizes Bluetooth technology to identify interactions between individuals who have tested positive for COVID-19 and others. This system informs users of potential exposures without collecting or sharing any personally identifiable information or location data. It employs a constantly changing, randomized identifier to signal potential exposure to nearby devices, while allowing individual state health departments to define specific parameters, such as the required proximity and duration of contact to be considered a risk.

Specifically within California, an exposure notification will be triggered when a user is within six feet of someone who has tested positive for COVID-19 for a duration of 15 minutes or longer. Individuals receiving a positive COVID-19 test result will receive a text message from the state’s Department of Public Health, including a unique code to be entered into the CA Notify app. This action initiates a broadcast alert to any phones that met the established criteria within the preceding 14 days – the timeframe during which the virus is considered contagious.

As previously noted, the notification system does not transmit any personal data from a user’s device, and participation is entirely voluntary. Numerous other states, along with many nations globally, have already implemented exposure notification applications based on the Apple/Google API. While it doesn’t substitute for traditional contact tracing – where healthcare professionals work to identify a COVID-19 patient’s contacts to understand transmission patterns – it serves as a beneficial addition to a thorough tracing program, enhancing its effectiveness and overall success.