The substance of nucleic acid detection is the nucleic acid of virus. Nucleic acid detection is to determine whether the patient is infected by COVID-19 by detecting whether there is nucleic acid of foreign invasive virus in respiratory tract samples, blood or feces. Therefore, once the nucleic acid is "positive", it can prove that there is a virus in the patient. After COVID-19 infects the human body, it will propagate in the respiratory system first, so we can judge whether the human body is infected with virus by detecting the virus nucleic acid in sputum and nasopharyngeal swab. Therefore, positive nucleic acid detection can be used as the gold standard for the diagnosis of novel coronavirus infection.
All living things except prions contain nucleic acids, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Novel coronavirus is a virus containing only RNA, and the specific RNA sequence in the virus is a sign to distinguish the virus from other pathogens. After the appearance of novel coronavirus, Chinese scientists completed the analysis of the whole genome sequence of novel coronavirus in a very short time, and found the specific nucleic acid sequence in novel coronavirus by comparing with the genome sequences of other species. If novel coronavirus's specific nucleic acid sequence can be detected in patients' samples during clinical laboratory testing, it should be suggested that patients may be infected by novel coronavirus.