In diagnosing novel coronavirus pneumonia, a crude or probable diagnosis is called a suspected case and a definitive diagnosis is called a confirmed case. Some of the suspected cases will end up with a confirmed diagnosis of novel coronavirus pneumonia, and some will be excluded from the diagnosis. The conditions for a suspected case are epidemiologic history and clinical presentation. Epidemiologic history has four conditions: 1. History of travel or residence in an infected area or other case-reporting community within 14 days prior to the onset of fever. 2. History of contact with a person infected with the new coronavirus (a person with a positive nucleic acid test) within 14 days prior to the onset of fever. 3. History of contact with a person with fever or respiratory symptoms from an infected area or case-reporting community within 14 days prior to the onset of fever. 4. History of contact with a patient from the infected area or case-reporting community within 14 days prior to the onset of fever. or patients with respiratory symptoms.4. Clustered onset of illness. Three conditions of clinical presentation: 1) Fever and/or respiratory symptoms. 2) Imaging features of novel coronavirus pneumonia. 3) Normal or decreased leukocyte count and decreased lymphocyte count in the early stages of the disease. 4) A history of a suspected case. Conditions for a suspected case: 1. Any 1 of the epidemiologic history, consistent with any 2 of the clinical manifestations. 2. No clear epidemiologic history, consistent with any 3 of the clinical manifestations. The next step is to perform nucleic acid positivity or viral gene sequencing of the novel coronavirus, which is highly homologous to known novel coronaviruses to confirm the diagnosis as a confirmed case.