Some patients with novel coronavirus pneumonia have no fever or only low-grade fever and mild symptoms, i.e., mild patients. Based on clinical manifestations, patients with novel coronavirus pneumonia can be categorized into four types: mild, common, severe, and critical. Mild patients may have no fever or only a low-grade fever with mild symptoms such as malaise and dry cough. Asymptomatic infections are those who are infected with novel coronavirus pneumonia and are contagious, but do not have symptoms of fever, cough and malaise, and have a completely normal chest CT with only a positive nucleic acid test. Infectious fever is caused by the release of toxins from the pathogen, which causes an increase in body temperature, or by the toxins released by the pathogen, which in turn induces the body to release cytokines, which and the toxins act as a pyrogenic source of the increase in temperature. Elevated body temperature is beneficial in the fight against viruses, making it easier for the body to mobilize the resistance system and stimulate immunity to clear the virus. Excessive body temperature can be detrimental, and higher body temperatures are often indicative of a more severe illness. Uniquely in novel coronavirus pneumonia, many people with severe, critically ill viral infections do not show a fever. Therefore, it is not possible to determine the severity of the infection based on the presence or absence of fever or the level of body temperature. Source: Dr. Yurai