Liang Lianchun, director and chief physician of the Center for Infectious Diseases at Beijing Youan Hospital, presented information about clinical tests and imaging examinations for New Crown Pneumonia. He said that experts currently do not recommend nucleic acid testing and chest imaging screening for people without symptoms such as fever or cough, and that serum-specific antibody IgG and IgM testing is not suitable for screening patients in the early stages of the disease or virus carriers who have not yet developed the disease.

According to the introduction, the "Novel Coronavirus Pneumonia Treatment Protocol (Trial Version 7)" issued by the National Health and Wellness Commission specifies that nucleic acid testing, serum-specific antibody test results and chest imaging changes are important judgment criteria for case diagnosis and discharge. "What tests are needed to determine a suspected case or a confirmed case when a patient visits a clinician based on the patient's symptoms, clinical tests and epidemiological history." Liang Lianchun said.

"Nucleic acid testing has the advantages of being early, sensitive, highly specific and easy to perform, but the accuracy of nucleic acid test results is related to the timing of the patient's infection and factors such as sample collection, reagent quality and experimental testing." Liang Lianchun explained that the main influencing factors are, first, the timing of specimen collection, the amount of virus in the patient's body in the early stage of the disease is small, not easy to detect and find; second, the respiratory specimen collection site, collection volume, preservation methods and time, etc.; third, the sensitivity of the new coronavirus nucleic acid detection kit.

"Therefore, for cases with high clinical suspicion, we usually need to repeatedly collect respiratory specimens, use 2 or more reagents for testing or verification, or perform virus-specific antibody IgM and IgG tests and other methods to make a diagnosis after a comprehensive determination.

Because of the long waiting time for nucleic acid testing and the limitations of the timing of sampling, it is generally not used alone for infection screening of the general population." Liang Lianchun said.