1, and the nucleic acid detection substance is the nucleic acid of the 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.
2. 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 the 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.