Effective January 17, 2023
About Wisconsin Exposure Notification
WI Exposure Notification allows users to send and receive notifications of a potential high-risk exposure to COVID-19, in a privacy-preserving manner. The notifications will include instructions on who to contact and next steps to take.
The exposure notifications are intended to supplement the conventional contact tracing efforts undertaken by local public health authorities involving contact by a caseworker.
How it works
WI Exposure Notification does not any personal information of the user, as defined in Wis. Stat. § 134.97(1)(e) to receive notifications.
The mobile devices of users share anonymous keys (randomly generated strings of numbers) via Bluetooth. The only data used are the anonymous keys, Bluetooth signal strength (proximity), and date and duration of exposure. These data are not linked to a user’s identity or location. Each user’s keys change frequently to further protect their identity. These data are stored only on the user’s device and are never shared unless and until the user has a positive COVID-19 diagnosis and elects to share this information within the system. The data are stored for a period of 14 days and then automatically deleted. Once deleted the data cannot be restored.
A user who tests positive for COVID-19 may choose to notify other WI Exposure Notification users who have been near the user. To trigger such notification, the COVID-19 positive user can use the “Share a COVID-19 diagnosis” option in the app. If you self-report a positive COVID-19 diagnosis, the app will request your phone number so as to be sure you don’t report more than one positive result over the course of 30 days. At that time, the app deletes your phone number.
Several times a day, the app connects with a national server to download a list of all the anonymous keys associated with positive COVID-19 cases that have elected to share their keys via the app. The user’s device checks these keys against the list of keys it has encountered in the past 14 days. If there is a match, and the date, duration, and proximity align with the public health authority’s risk model to indicate a possible exposure to the virus, the user will receive an exposure notification.
The notification will inform the user of the date of exposure and instructions on what to do next.
User consent and choices
Using the system
WI Exposure Notification has the potential to help stop the spread of the infection and its use is highly encouraged, but it is completely voluntary.
Users may turn the system on or off at any time, or uninstall the app on an Android device. The system does not collect, track, or store users’ location or GPS information.
Disabling exposure notifications
Users may disable WI Exposure Notification at any time by uninstalling the app (Android), turning off the feature (iOS), turning off the mobile device, or turning off the Bluetooth function.
Generating exposure notifications to other users
Providing notification to other users is also completely voluntary. If a user tests positive for COVID-19, and chooses to notify others, the user has to activate notifications by choosing "Share a COVID-19 diagnosis" and following the instructions given to release the anonymous keys stored on the mobile device. When anonymous keys are released, the notifications that may be generated do not disclose the COVID-19 positive user’s identity, location, phone number, or any other personal information.
The exposure notification includes a two-day exposure window, but the COVID-19 positive user’s identity is not shared. Sharing the exposure date is important to ensure the right precautions (such as masking) are taken for an appropriate amount of time based on the exposure date. It is possible that someone who receives an exposure notice could guess the identity of the COVID-19 positive individual, if they had a limited number of contacts on a given day.
Sharing of information
The following categories of de-identified data may be processed and collected by WI Exposure Notification unless a user opts out:
- App installation and deletion metrics
- Exposure notification metrics
- Exposure notification interaction metrics
- Key upload metrics
- Verification code metrics
- Anonymous keys that have been voluntarily shared
The data may be used to monitor system usage, as well as for performance evaluation and statistical or scientific research purposes. This data is only collected if you explicitly opt in. The data may also be shared with local public health authorities. This information will not include any personal or location information, nor can it be used to identify any system user.
WI Exposure Notification is not intended for use by anyone under the age of 18.
This application is not a substitute for medical advice. Users of the application should consult their health care professional before making any health, medical, or other decisions based upon the data contained within. Use of the app is at your own risk. This app is released as is, without any warranty, responsibility, or liability.