Asymptomatic infections are generally used to describe the diagnostic type of new crown pneumonia. Asymptomatic infection means that the infected person does not have imaging symptoms such as pneumonia not seen on lung CT, and its emergence is mainly affected by immunity, vaccination, and viral pathogenicity. 1. Immunity: If the patient’s immunity is normal or strong, and the body contains an immune barrier against the virus, even if the virus exists in the human body, it will be easily removed by the body’s immune mechanism, and will not easily cause the body’s immune response, and there will be no manifestation of pneumonia on lung CT. 2. Vaccination: If the patient is vaccinated, the antibody has the ability to recognize the virus, and when the virus just invades the human body, the protective effect of the vaccine will be the first time to control the replication and spread of the virus, so that the amount of its presence in the body and the virulence of the body is at a lower level, so even if the infection, some patients do not have inflammation under the CT of the lungs manifestations. 3. Pathogenicity: the presence or absence of symptoms is related to the virulence of the virus, such as omicron viruses compared to Delta virus virulence has been reduced, the human body’s immunity to fight against it will be lighter, the symptoms will not be very obvious, or even manifested in the absence of lung CT imaging symptoms. There are many other causes of asymptomatic infections, such as the presence of other co-morbidities that affect the immune response, and it is important to seek medical attention at the onset of an infection to avoid exacerbation of the disease. Tip: In this article, the terms “new coronavirus pneumonia” and “new coronavirus pneumonia” were renamed to “new coronavirus infection” in a public announcement issued by the National Health Commission on December 26, 2022, and are now referred to as “new coronavirus infection”.