When infected with a novel coronavirus, the virus enters the epithelial cells of the human respiratory tract, where it proliferates and multiplies, destroying the cells and spreading to other cells. In fact, the diagnosis of novel coronavirus is mainly based on the pathogenic examination when the virus enters the cells initially, and the presence of viral nucleic acid can be detected by PCR. Because patients with novel coronavirus infection can be of different types clinically, such as the mild type without typical clinical manifestations or even without onset of disease, it is difficult to determine the presence of novel coronavirus infection without virus testing. Patients with the common type have symptoms of cough, fever, and dyspnea, but these are often non-specific clinical manifestations, so viral nucleic acid testing is required to determine the presence or absence of novel coronavirus infection. In addition to nucleic acid testing, the virus can be sequenced, and viral sequencing can also be called reliable evidence of infection with the virus. Content source: Dr. You Lai