1. Key Laboratory Medical Molecular Virology, MoE/MoH, and the Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
2. Laboratory of Molecular Biology, Training Center of Medical Experiments, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
3. Zhengding County Center for Disease Control and Prevention, Zhengding 050800, Hebei Province, China
4. Hebei Province Center for Disease Control and Prevention, Shijiazhuang 050800, Hebei Province, China
5. Department of Health Statistics, Fourth Military Medical University, Xi’an 710032, Shanxi Province, China