What are “contact tracing” and “exposure notification?” Specifically, how is the Safer Badgers app using track-and-trace technology to manage COVID-19 cases?

“Contact tracing” is a public health procedure used to identify people who may have come into contact with an infected person. Public health workers who conduct contact tracing interview known infected individuals, attempt to identify all recent contacts of the infected individual, and then follow up with those contacts by recommending testing, quarantine, treatment or other measures.

UW-Madison University Health Services manages contact tracing for those individuals who test positive for COVID-19 at on-campus testing locations. UHS works closely with the contact tracers at Public Health Madison and Dane County (PHMDC). PHMDC contact tracers can be used to supplement university contact tracing capacity in surge situations.

“Exposure notification” lets people know if they were in the vicinity of someone who was later found to be infected. The Safer Badgers app provides exposure notification for those users who enable this feature.

If users enable exposure notification, their phones store Bluetooth-emitted tokens when they are in sufficient proximity to other phones. If users of the app later find out they are infected, 14-days of their Bluetooth tokens are uploaded to a secure database server and then downloaded by other phones. Then those phones look for matches with the tokens they have saved.

Phones that find matches notify their users that they might have been exposed. Exposure notifications are generated on each user’s phone, and the notification is displayed only on the user’s phone. Individual exposure notifications are not reported to any other party.

Summary statistics about exposure notifications are reported to University Health Services. The Safer Badgers app never tracks geolocation (i.e., GPS, or Global Positioning System).