1. Department of Chronic Communicable Disease, Center for Disease Control and Prevention of Jiangsu Province, Nanjing, Jiangsu Province, People’s Republic of China
2. Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu Province, People’s Republic of China
3. Division of Infectious Diseases and Geographic Medicine, School of Medicine, Stanford University, Stanford, California, USA
4. Center for Disease Control and Prevention of Danyang City, Zhenjiang, Jiangsu Province, People’s Republic of China