Expert Answers | Which groups of people are suitable for antigen testing? What if the self-test result is positive?

People’s Daily Online, Changchun, March 18 (Li Yang) Today, the 39th press conference on epidemic prevention and control in Jilin Province was held by video link. Tong Xueying, director of the Jilin Provincial Clinical Laboratory Center, answered reporters’ questions on which groups of people are suitable for antigen testing and how to deal with residents’ self-test positive.

Tong Xueying said that antigen testing is mainly suitable for three groups of people: the first is people who go to primary medical and health institutions for treatment, have respiratory symptoms, fever and other symptoms and have symptoms within 5 days. The second is isolation observation personnel, including home isolation observation, close and sub-close contact, entry isolation observation, closed and controlled areas and personnel in control areas. The third type is community residents who need antigen self-testing.

Tong Xueying introduced that antigen detection is faster and simpler than nucleic acid detection, but its sensitivity is not as good as nucleic acid detection. At this stage, nucleic acid testing is still a basis and a “gold standard” for determining new crown infection, so antigen testing cannot replace nucleic acid testing. If a community resident has a positive antigen test, regardless of whether they have respiratory symptoms, fever and other symptoms, they should immediately report to the community (village) where they live, and the community (village) will contact the emergency center to transfer the residents to Set up medical institutions with fever clinics to conduct nucleic acid testing for confirmation.

It is reported that, in order to further optimize the new coronavirus detection strategy, serve the needs of current epidemic prevention and control, further achieve early detection and early triage management of new crown patients, and improve the sensitivity of detection and early warning, based on the national plan, on the basis of nucleic acid detection, Changchun City has increased Antigen detection methods are supplemented.

Antigen detection is detected on a test strip through an antigen-antibody binding reaction (it measures the highly expressed nucleocapsid protein of the new coronavirus, that is, the N protein). result. Not limited by equipment and venues. The sensitivity and specificity of antigen detection are worse than nucleic acid detection, especially the sensitivity. The sensitivity of nucleic acid detection analysis is about 100 to 1000 times higher than that of antigen. Therefore, it is generally used in the acute infection period (the period when the viral load in the patient is high), that is, the detection of samples within 7 days of the onset of symptoms. Positive antigen test results can be used for early triage and rapid management of suspected populations, but cannot be used as the basis for the diagnosis of new coronavirus infection.