1. Division of Prevention and Intervention, National Center for AIDS and STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
2. Henan Provincial Center for Disease Control and Prevention, Zhenzhou, Henan, China.
3. Kunming Center for Disease Control and Prevention, Kunming, Yunnan, China.
4. Guangzhou Center for Disease Control and Prevention, Kunming, Yunnan, China.
5. School of Health Service Management, Anhui Medical University, Hefei, Anhui, China.