The diagnosis of novel coronavirus infection requires a comprehensive analysis of epidemiological history, clinical manifestations and laboratory tests. Epidemiologic history: 1. Record of travel to the place of origin of the outbreak or other infected areas within 14 days before the onset of the disease. 2. Contact with patients with fever and respiratory symptoms from infected areas or other infected areas within 14 days before the onset of the disease. Clinical manifestations: 1. fever. 2. chest imaging tests with small patchy shadows and interstitial changes, or multiple glassy shadows in both lungs or substantial lung lesions. 3. normal or reduced total white blood cell count, or reduced lymphocyte count. When one of the epidemiological history and two of the clinical manifestations are satisfied, one of the following pathogenic evidence is also present: 1. Positive nucleic acid of novel coronavirus by real-time fluorescence RT-PCR of respiratory specimen or blood specimen; 2. Viral gene sequencing of respiratory specimen or blood specimen, which is highly homologous with known novel coronavirus, can confirm the diagnosis of novel coronavirus infection.