Infectious diseases have a clear source of infection, new coronavirus infectious source is mainly patients with new coronavirus infection, patients through the cough, respiratory droplets infectious disease, that is, mainly through the respiratory route of transmission, close contact can also be transmitted, such as hand contact with the virus and then rubbing eyes, rubbing nose can also be transmitted. As the disease progresses, some patients are asymptomatic infections, no fever, cough and other clinical manifestations, but patients pharyngeal secretions, sputum to nucleic acid positive, these patients can also be infectious. In particular, asymptomatic infected patients, although there is no clinical manifestation, but there is virus reproduction in the respiratory tract, through the cough to spread the virus into the air, causing interpersonal transmission, is the more difficult and challenging part of this new coronavirus infection prevention and control. Because this asymptomatic infection is more difficult to detect than in patients with symptoms, prevention and control is more difficult. Content source: Dr. Yurai