<https://www.thecrimson.com/article/2020/8/2/tracefi-wifi-contract-tracing-co...> Harvard began piloting Tracefi — a Wi-Fi-based contact tracing system — this past Friday in preparation for freshmen and a select group of upperclassmen students’ return to campus later this month. Tracefi uses the signals phones, laptops, and tablets constantly emit to Harvard’s Wi-Fi infrastructures to gather three pieces of information: a datetime stamp, the signal strength received by Harvard’s Wi-Fi infrastructure, and the MAC address of the mobile device. The system then stores the data for up to 28 days. Harvard will use the Tracefi data to aid contract tracing efforts run by Harvard University Health Services and Harvard University Information Technology by providing information to human contact tracers about the specific whereabouts of infected individuals. “We all want Harvard to return to lab research and on-campus activities safely, and we want our undergraduates to return to campus too,” Tracefi’s website reads. “One of the safety precautions Harvard wants in place to achieve this vision is the ability to notify a person who was in a building that she came into contact with someone who later tested positive for COVID-19. Timely notification can help her seek prompt testing for herself and protect her family and others from exposure.” The website explains that the data collected from the Wi-Fi information does not contain personally identifiable information, and that HUHS will only access relevant data if a patient tests positive for COVID-19. People can choose to opt-out of Tracefi by turning off Wi-Fi service on their device, the info page for the program notes. [...]