There are common cold and influenza. The common cold manifests as fever, but the fever does not last long, usually relieved in 2-3 days, accompanied by runny nose, sneezing and sore throat. The routine blood leukocytes are not high, lymphocytes are relatively high for classification, and there are no obvious changes in the CT of the lungs. Influenza is actually influenza, a viral infection, which is characterized by a certain epidemic nature and relatively heavy symptoms, starting with a fever of 39℃ or higher, accompanied by body aches and pains, but no obvious changes in the lung CT, which can be accompanied by a series of symptoms such as sore throat, runny nose and cough. Blood tests may show a high lymphocyte count, and a pharyngeal swab may be done to differentiate between influenza A and influenza B infections. Novel coronavirus pneumonia is also a viral infection, but the site of infection is the lungs. The clinical manifestations are mainly fever, which is not particularly severe, usually around 38°C. The duration of fever is relatively long, usually more than 3 days, and may be accompanied by symptoms of malaise. The symptoms of upper respiratory tract infection are not obvious, i.e. the symptoms of nasal discharge, sneezing and sore throat are not obvious, mainly dry cough. The lung CT has blur-like hairy glass-like changes in both lungs. Blood work will reveal that the patient’s total white blood cell count may not be significantly elevated, but the lymphocyte count is progressively decreasing. In addition, the common form of bacterial pneumonia is also inflammation of the lungs, but the inflammation of the lungs is caused by a bacterial infection, and this patient is characterized by fever with pus and yellow sputum, which may also be accompanied by muscle aches. The blood count is significantly elevated and the neutrophil count is also significantly elevated. The CT of the lung is usually unilateral with a lamellar shadow. Content source: Dr. You Lai