On Wednesday, the Virginia Department of Health released its official COVID-19 exposure notification app, and it is the first in the United States to use the Google and Apple API.
Canada was one of the first countries with such an app, releasing it at the end of July. The app relied upon Canada's health system to inform the app of a diagnosis.
The Virginia app is called COVIDWISE and works similarly. When you have been diagnosed by a doctor, you must complete a questionnaire in the app to alert other users of the diagnosis. When logging this data, it is only to verify a positive result, and does not expose your personal information to others.
When the app is enabled, it will run in the background with no interaction from the user. If the phone determines that you have been close to another individual using the app for an extended period of time, it will store those credentials shared by the other phone.
The system uses bluetooth to exchange tokens and will not have noticeable effects on battery life.