iOS 13.7 introduced Exposure Notifications to the iPhone in the height of the pandemic. Unlike other mobile notification features, the COVID-19 Public Health Authority alert system arrives disabled on your device. This means if you'd like to receive exposure updates, you'll need to enable them on your device. When enabled your phone will search for other iOS and Android devices with Exposure Notifications turned on. Users can report if they have tested positive and anonymously notify those who have been near them. If you have been exposed your public health authority can then notify you through your device.
You can enable and disable Exposure Notifications in the Settings app. Just open the app on your device and scroll down until you locate the Exposure Notifications tab. Tap the tab then tap the Availability Alerts slider so it's GREEN/ON. Tap it again to disable notifications.