(1) diseases need to be differentiated from 2019-ncov, such as influenza virus, parainfluenza virus, adenovirus, respiratory syncytial virus, rhinovirus, human partial pulmonary virus, SARS coronavirus and other known viral pneumonia, mycoplasma pneumoniae, chlamydia pneumonia, bacterial pneumonia and non-infectious diseases, (2) suspected case of 2019-ncov with no confirmed patient, (3) the clinical stage was mild: the clinical symptoms were mild, and no pneumonia was observed on imaging, (4) clinical stage: common type: fever, respiratory tract and other symptoms, and imaging findings of pneumonia, (5) have any known disease that seriously affects the immune system, such as a history of infection with the human immunodeficiency virus (HIV), or malignant tumors of the blood system or solid organs, or splenectomy, (6) other circumstances that the researcher considers inappropriate to participate in this study.

(1) diseases need to be differentiated from 2019-ncov, such as influenza virus, parainfluenza virus, adenovirus, respiratory syncytial virus, rhinovirus, human partial pulmonary virus, SARS coronavirus and other known viral pneumonia, mycoplasma pneumoniae, chlamydia pneumonia, bacterial pneumonia and non-infectious diseases, (2) suspected case of 2019-ncov with no confirmed patient, (3) the clinical stage was mild: the clinical symptoms were mild, and no pneumonia was observed on imaging, (4) clinical stage: common type: fever, respiratory tract and other symptoms, and imaging findings of pneumonia, (5) have any known disease that seriously affects the immune system, such as a history of infection with the human immunodeficiency virus (HIV), or malignant tumors of the blood system or solid organs, or splenectomy, (6) other circumstances that the researcher considers inappropriate to participate in this study.