1. Department of National Immunization Program, Fujian Provincial Center for Disease Control and Prevention, Fuzhou, China
2. National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
3. National Institute of Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
4. Department of Clinical Epidemiology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China