https://techcrunch.com/2020/04/20/facebooks-covid-19-survery-cmu-delphi-google/

Many, many symptom trackers have launched during the coronavirus pandemic, but few have the potential to reach even a bucketful of Facebook’s vast ocean of users.

Facebook launched a symptom tracking partnership with Carnegie Mellon University’s Delphi epidemiological research center early this month, and now the company plans to expand the project outside of the U.S. In early April, Facebook began prompting some users in the U.S. with a CMU survey asking them to self-report COVID-19 symptoms. The effort is designed to help governments and health officials predict where the virus could hit next.