Risk factors for the critical illness in SARS-CoV-2 infection: a multicenter retrospective cohort study oleh Sijing Cheng, Dingfeng Wu, Jie Li, Yifeng Zou, Yunle Wan, Lihan Shen, Lixin Zhu, Mang Shi, Linlin Hou, Tao Xu, Na Jiao, Yichen Li, Yibo Huang, Zhipeng Tang, Mingwei Xu, Shusong Jiang, Maokun Li, Guangjun Yan, Ping Lan, Ruixin Zhu