Antigen self-testing is generally referred to as neocoronavirus antigen self-testing, and unclear results may be caused by errors in use or contamination of the kit. When performing antigen testing, it is necessary to follow the instructions strictly to avoid invalid results. When there is no band at “C”, regardless of whether or not a band is shown at “T”, the test result is invalid, in which case the kit should be replaced and retested. When performing antigen testing, check for broken or missing swabs before sampling. The swab should be left in the nasal cavity for more than 15 seconds. Blow your nose before sampling to avoid affecting the test results. The swab head is placed in the preservation fluid and swirled and mixed for more than 30 seconds before dropping the fluid vertically into the sample hole of the test card and waiting for 15 minutes to observe the result. Antigen self-tests that show abnormal results cannot be used as a basis for a definitive diagnosis, and a series of follow-up tests, such as nucleic acid testing, are required.