Here’s how it will work, from The Verge’s report on the announcement:

Under the new system, participating health departments will assemble a configuration file, allowing them to set their risk scores, redirect users to their specific health department website, and modify the recommendation for users who have been exposed. Once the configuration is complete, iOS and Android can automatically generate the necessary software, although the two operating systems handle the task differently. In Android, the configuration file will automatically generate a custom Android app, while iOS will incorporate the settings into its OS-level contact system.

More generally, the OS-powered touch monitoring device is configured to warn someone when they might have been in communication with another person who was subsequently diagnosed with COVID-19, mainly via a dynamic BLE Beacon protocol. Protocol support was first introduced to iOS in May with the introduction of iOS 13.5. At the point, though, every state wanted an app produced by the public health department that used the API. Now, however, states will simply supply Apple and Google with the details they need, and the auto-generated tech system can take care of the rest.

Apple and Google have made it clear that the current applications, of which there are six, will continue to function and that inter-state interoperability is integrated into the latest platform to ensure communication monitoring of state lines. The first official program to endorse the exposure warning scheme was released in Virginia earlier in August. Last month, the University of Alabama in Birmingham also unveiled a closed pilot for an exposure warning app.

"As the next step in our collaboration with public health agencies on Exposure Alerts, we are making it simpler and quicker for them to use the Exposure Alert Framework without the need for them to create and operate an app," said Apple and Google today in a joint statement. "Exposure Alerts Express offers a further alternative for public health agencies to add technologies to their current contact tracing activities without violating the basic values of consumer privacy and protection of the initiative.Current systems using the Exposure Warning API will be compliant with Exposure Alerts Express and we are committed to helping public health agencies who have implemented or are creating custom applications.