1. Department of Epidemiology and Biostatistics, School of Public Health, Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region , P.R. China
2. Department of Community Medicine, Faculty of Medicine and Health Sciences, Thamar University , Dhamar, Yemen
3. Department of Endocrinology, Internal Medicine, The First Affiliated Hospital of Guangxi Medical University , Nanning, Guangxi, P. R. China
4. Acute Infectious Disease Prevention and Control Branch, Xiamen Center for Disease Control and Prevention , Xiamen, Fujian, P. R. China
5. Department of Immunology & Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Hebei Medical University , Shijiazhuang, China
6. Department of Microbiology, National Program for Bacterial Meningitis Investigation, Dhamar General Hospital , Dhamar, Yemen
7. Department of Central Supervision, Expanded Program on Immunization, Ministry of Public Health Population , San'a, Yemen
8. Department of Epidemiology, Faculty of Medicine, Prince of Songkla University , Hat Yai, Songkhla, Thailand