https://techcrunch.com/2020/10/19/eu-switches-on-cross-border-interoperability-for-first-batch-of-covid-19-contacts-tracing-apps/

The European Union has switched on cross-border interoperability for a first batch of COVID-19 contacts tracing apps that use Bluetooth proximity to calculate the exposure risk of smartphone users after a pilot of the system last month.

National apps whose backends are now linked through the gateway service are Germany’s Corona-Warn-App, the Republic of Ireland’s COVID tracker, and Italy’s immuni app.