At present, the research results show that the main source of infection is patients infected with novel coronavirus. Asymptomatic or mild recessive infection may also become the source of infection, because asymptomatic infection has relatively hidden clinical symptoms, which makes the infection in novel coronavirus difficult to control and easy to cause the accumulation of infectious sources in the community. Second: What if an asymptomatic infected person has COVID-19's symptoms? If COVID-19 has symptoms such as fever, cough, stuffy nose, runny nose and chest tightness, it will become a confirmed case, indicating that the virus concentration in the body will be high, that is, it will become a carrier of COVID-19 virus. Therefore, asymptomatic infected people must be strictly isolated and observed. Treatment of cases with confirmed symptoms: 1. Stay in bed, strengthen supportive treatment, and ensure adequate heat; Pay attention to the balance of water and electrolyte and maintain the stability of internal environment; Closely monitor vital signs, blood oxygen saturation, etc. 2. Monitor blood routine, urine routine, CRP, biochemical indexes (liver enzyme, myocardial enzyme, renal function, etc. ), coagulation function, arterial blood gas analysis, cytokine detection if possible, and chest image review. After patients are infected with novel coronavirus, there will be symptoms of lung infection, of which dry cough is the most common. After taking antibiotics and other drugs on their own, some early patients' symptoms will be slightly mild, but their condition will get worse in a short time. Fatigue, after the patient was infected with novel coronavirus, the respiratory system and digestive system were attacked by viruses, and their functions declined. At this time, the patient will be weak. Without further medical intervention, many complications may occur, such as hypoxemia, acute respiratory distress, sepsis, metabolic acidosis and other serious diseases.