1. Department of Social Welfare, UCLA Luskin School of Public Affairs, Los Angeles, California, USA.
2. Department of Global Health, University of Washington, Seattle, Washington, USA.
3. Department of Epidemiology, University of Washington, Seattle, Washington, USA.
4. Department of Medicine, University of Washington, Seattle, Washington, USA.
5. Department of Psychology, University of Washington, Seattle, Washington, USA.
6. Danlan Beijing Media Limited, Beijing, China.
7. National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.