A positive new crown antigen test but a negative nucleic acid test may be a false positive due to a failure to perform the procedure correctly, sample contamination, or problems with the antigen reagent.
1. Failure to operate correctly: In antigen detection, after sampling, the swab with the sample needs to be put into the extraction tube containing preservation solution to be mixed and squeezed, and then dropped vertically into the detection hole, if the operation is not standardized in this process, it may lead to sample results by the influence of acidity and alkalinity and errors.
2. The sample is contaminated: In antigen testing, if the sample is in contact with other objects or exposed to air for too long after sampling, the sample may be contaminated, which may lead to incorrect results.
3. Antigen detection itself has a margin of error: at present, antigen detection, as an addition to nucleic acid detection, allows for a certain margin of error in the degree of sensitivity, so the test results may appear false positive.
Therefore, when performing antigen testing, it is recommended to follow the procedure as closely as possible to avoid sample contamination or excessive delay. In the case of a positive antigen test but negative nucleic acid test, it is generally necessary to report the case promptly and maintain isolation, and if necessary, repeat the nucleic acid test for review.