1. Division of Hospital Infection Control and Prevention, Beijing Hospital, National Center of Gerontology, Beijing, China.
2. Division of Hospital Administration Office, Beijing Hospital, National Center of Gerontology, Beijing, China.
3. Division of Emergency Department, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, China.
4. Division of Hospital Infection Control and Prevention, Peking University People's Hospital, Beijing, China.