We are indebted to Prof. Tie Chen and Prof. Daowen Wang, who helped to prepare and review the manuscript. We also thank Drs. Yanping Cai, Yin Lv, Jia Chen, Nana Xie, Jiling Zhu, Mingyou Xing, Yuan Song, Chaolin Huang, Li Zhang and Xingjie Hao for collecting cases or scientific support. And we gratefully acknowledge all the health care workers on the front line and all the patients involved in the study.