1. Department of Virology, School of Public Health, Cheeloo College of Medicine, Shandong University, Ji'nan, Shandong, China.
2. Department of Health Management and Services, Cangzhou Medical College, Cangzhou, Hebei, China.
3. Department of Clinical Laboratory, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Ji'nan, Shandong, China.