1. Respiratory Department, Hebei Chest Hospital, Shijiazhuang, P.R. China.
2. Respiratory Department, Hebei Hospital of Traditional Chinese Medicine, Shijiazhuang, P.R. China.
3. Intensive Care Unit, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, P.R. China.
4. Infectious Disease Department, The Second Hospital of Hebei Medical University, Shijiazhuang, P.R. China.
5. Infectious Disease Department, Beijing Ditan Hospital, Capital Medical University, Beijing, P.R. China.