Institution: | 1. Department of Epidemiology and Medical Statistics, Jilin University School of Public Health, Changchun, P.R. China;2. National Center for AIDS/STDs Control and Prevention, Chinese Center for Disease Control and Prevention, 27 Nanwei Road, Xuanwu District, Beijing 100500, P.R. China;3. Kaiyuan Center for Disease Control and Prevention, Yunnan, P.R. China |