Bits and Bytes Blog
Getting COVIDWISE: Learn About Virginia’s Official Exposure Notifications App
Wednesday, August 19, 2020
On August 5, 2020, the Virginia Department of Health launched COVIDWISE, an innovative exposure notification app that will alert users if they have been in close contact with another app user who has tested positive for COVID-19.
While similar apps had been developed throughout the U.S. and around the world prior to the release of COVIDWISE, Virginia was the first state in the country to design and release a COVID-19 app using Bluetooth Low Energy technology developed by Apple and Google, which does not rely on or collect personal information or location data.
Since the launch, COVIDWISE has been downloaded more than 547,000 times, which means that about 14% of Virginias with smartphones have downloaded the app on their iPhones and Android devices. Studies show that for every two people who download COVIDWISE, one future infection is potentially prevented.
How COVIDWISE Works:
Once a user downloads COVIDWISE, which is available for free in Apple’s App Store and Google Play, and opts-in to the notification system, the Exposure Notifications System generates an anonymous token for the user’s device and allows smartphones to exchange these anonymous keys over Bluetooth. To help ensure these anonymous tokens can't be used to identify the user or their location, they change every 10-20 minutes. Each phone shares its own daily anonymous key and stores the anonymous keys of nearby devices locally (i.e. on the user’s phone) for 14 days. On a daily basis, the app downloads a list of all the anonymous tokens associated with positive COVID-19 cases and checks them against the list of anonymous tokens it has encountered in the last 14 days.
When people who have downloaded the app are near each other for a period of time determined by VDH to represent a risk (a period which is updated based on the latest research), their phones exchange and save the anonymous key of the other phone.
Alongside the anonymous key, phones estimate the contact risk of an exchange using the date, time, and the duration of the contact, as well as the strength of the Bluetooth signal (to approximate distance). Contact risk is used to determine if a user is notified of a potential exposure and is not shared with any user.
If an app user is tested and diagnosed with a positive case of COVID, they are given an anonymous verification PIN by the VDH. The user can then use that PIN to submit a positive test result in the app to notify others. Once submitted, other app users that they were near can expect to receive an exposure notification within the next day or so from the time the report was submitted. This time is needed to make the positive user’s tokens available on the server and for other users’ devices to download those tokens and check for potential matches. If there's a match, the app will notify those users and offer further instructions from VDH on how to get tested and keep themselves and the people around them safe.
Use of the COVIDWISE app is 100% voluntary and users may choose to install and uninstall the app at any time.
To learn more about COVIDWISE, and to add your phone to the COVID fight in Virginia, visit COVIDWISE.org.