1. Institute for Vaccine Clinical Research, Hebei Province Centre for Disease Control and Prevention, Shijiazhuang, People’s Republic of China
2. Department of Chronic Disease Prevention and Control, Laishui County Center for Disease Control and Prevention, Baoding, People’s Republic of China
3. Department of Medical Services, Beijing Zhifei Lvzhu Biopharmaceutical Co. Ltd, Beijing, People’s Republic of China