Statistics show relatively high usage rates for UArizona's exposure notification app, which helped curb the spread of the virus on campus. Public health experts say the digital strategy worked well because it was used in conjunction with traditional contact tracing, in addition to testing and isolation efforts.
Since the University of Arizona launched Covid Watch Arizona – an anonymous COVID-19 exposure notification app – in August, the app has had relatively high download and usage rates, and university analysts estimate that it may have helped reduce the average number of people infected on campus by 12%.
"That estimated 12% reduction in transmission matters. If you can get R(t) (the average number of people infected by a positive
person) to drop from 1.06 to .94, that translates from exponential growth to exponential decline," said Joanna Masel, a professor of in the UArizona Department of Ecology and Evolutionary Biology. Masel led the development of the app's risk scoring component, as a member of the UArizona Covid Watch implementation team and a consultant for WeHealth, the company that distributes the app.
The app is designed to anonymously alert users of exposure to COVID-19 and direct them to appropriate resources. Anyone can download the app, but its follow-up recommendations are tailored based on location. UArizona students, faculty and staff can select the University of Arizona as their region setting. The app is also in use at Northern Arizona University, where users can select NAU as the region.
Once installed, the app generates random, anonymous codes that are exchanged between app users' phones via Bluetooth. Users who test positive for COVID-19 can input a verification code from a lab, doctor or medical center; at UArizona, that code comes from Campus Health. The app then sends an exposure notification alert to other Covid Watch users whose phones were registered as recently being near the infected person's phone for a significant amount of time.
An estimated 14,000 people on the UArizona campus have downloaded the mobile app.
The app's technology was born from a research collaboration between Stanford University and University of Waterloo researchers, including Covid Watch Executive Director Tina White, who graduated from UArizona in 2007 and 2009 with bachelor's and master's degrees in aerospace engineering before pursuing a Ph.D. at Stanford.
New updates to the app, rolled out on Dec. 16, allow for more nuanced messaging about COVID-19 exposure. Previously, when app users received an exposure notification, it indicated either "no significant exposures" or "significant exposures." Depending on the length of exposure and other factors, users will now instead receive one of three exposure notifications: No exposure detected; low exposure, in which case users do not need to quarantine; or high exposure, in which case users are directed to self-quarantine and are provided information about testing.
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