Repost from information shared by Cynic, UK & Netherlands Expert:
Last week, a worldwide update was applied to all Android and iPhones. Basically, a COVID-19 exposure tracking/logging is added to our phones. If you have an Android phone, go under Settings, then Google settings and it's there. If you have an iPhone, go to settings, privacy, then health.
The tracking/logging only works via an app, which you can enable or ignore.