1. San Francisco Department of Public Health, San Francisco, California.
2. University of California, San Francisco, San Francisco, California.
3. University of Michigan School of Public Health, Ann Arbor, Michigan.
4. University of Washington School of Public Health, Seattle, Washington.
5. Stroger Hospital of Cook County, Chicago, Illinois.
6. University of British Colombia, Vancouver, Canada.
7. Gladstone Institute of Virology, San Francisco, California.