Wenzhou Li1, Shanquan Chen2, Jun Wang1, Lu Zhao3, Dan Wang4. 1. Puai hosptial, Wuhan, China. 2. School of Clinical Medicine, University of Cambridge, Cambridge, CB2 3EB, UK. Electronic address: sc2147@medschl.cam.ac.uk. 3. State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China. 4. Jockey Club School of Public Health and Primary Care, Chinese University of Hong Kong, Hong Kong, China.