This was a retrospective cross‐sectional observational study. All of the COVID‐19 pneumonia and influenza A pneumonia subjects were confirmed by laboratory tests and were admitted to Ningbo First Hospital. COVID‐19 pneumonia patients were hospitalized between January 1 and March 31, 2020, while influenza A pneumonia patients were hospitalized at the same period: All of the patients met the criteria to diagnose pneumonia as an acute respiratory disorder characterized by the presence of cough and at least one of the new‐onset focal chest signs, fever for more than 4 days or dyspnea/tachypnea. 12 Following fulfillment of these criteria, all of the patients with COVID‐19–induced or influenza A–induced pneumonia were included in this study. The study has been reviewed and approved by the Medical Ethical Committee of Ningbo First Hospital (2020‐R037). The requirement for written informed consent was waived for the urgent need to collect clinical data according to the policy for public‐health‐outbreak investigation of emerging infectious diseases issued by the National Health Commission of the People's Republic of China, and no potential harm could be done to patients in light of retrospective study.