Recently, many readers have reported that they have not turned negative after the sun. For example, Mr. Yang, 50, was still positive on the 20th day after he became positive. In response, Zhan Shaofeng, chief physician of the Department of Respiratory and Critical Care Medicine of the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, answered that generally speaking, patients infected with Omixon virus can turn negative after 5 to 7 days, but some patients do turn negative slowly in clinical practice, which may be related to a variety of reasons. The first is that the viral load of patients exposed to infection is relatively large, so it takes longer to clear the virus than other people, and then the negative turns slowly. The second is that it may be related to different infected strains, and the time of negative conversion of different strains is also different. Third, it is related to the patient's own immunity. Some patients have low immunity (for example, they have basic diseases, often stay up late and work overtime in the recent period, and are taking immunosuppressive drugs), or do not pay attention to rest after yang, resulting in slow clearance of the virus, and the virus still continues to replicate in the body, which may lead to delayed negative or positive recovery. This part of patients should be particularly careful. Because of their low immunity, COVID-19 infection is easy to combine with bacterial infection, leading to aggravation of the disease. Fourth, the possibility of re-infection should not be ruled out. Patients infected with COVID-19 will produce antibodies against this strain or similar strains, but from the information available at present, COVID-19 mutates very quickly, and the antibodies produced by the first infection may lose their protection against the mutated strain and become infected again in a short time. Zhan Shaofeng believes that the most common reason should be related to the patient's own immunity, so it is necessary to pay attention to rest, sleep more, strengthen diet and nutrition, reduce unnecessary going out, wear a mask when going out, and recuperate for a period of time. (Outlook New Era)