Published on in Vol 8, No 6 (2020): June
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/15890, first published
.
1 School of Public Health, University of California, Berkeley, Berkeley, CA, United States
2 Design for Health, IDEO, San Francisco, CA, United States
3 Facebook Research, Menlo Park, CA, United States