1. West China School of Public Health and West China Fourth Hospital, Sichuan University , Chengdu, Sichuan 610041 , China
2. Chongqing Center for Disease Control and Prevention , Chongqing 400042 , China
3. Department of Epidemiology, School of Public Health, Sun Yat-Sen University , Guangzhou, Guangdong 510275 , China
4. Infectious Disease Control Department, Chengdu Center for Disease Control and Prevention , Chengdu, Sichuan 610041 , China
5. Plateau Health Science Research Center, Medical School, Tibet University , Lhasa, Tibet 850000 , China
6. Tibet Center for Disease Control and Prevention , Lhasa, Tibet 850002 , China
7. School of Public Health, the Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University , Guiyang, Guizhou 550025 , China
8. Department of Epidemiology and Health Statistics, School of Public Health, Kunming Medical University , Kunming, Yunnan 650550 , China