Antigen test generally refers to the New Coronavirus antigen test, which does not show a red line is not normal. Antigen test kits generally have two sites that show a red line. The first red line shown is to determine if the antigen kit is valid, if the second site shows a red line, it is positive for the virus. Failure to show a red line is abnormal and may be due to the kit itself not meeting the requirements, improper storage of the kit, or improper use by the tester. This does not mean that the tester is negative for the virus. It is necessary to re-test using a qualified kit and adopting the correct test method. When using the test kit, it is necessary to do a good job of hand disinfection, carefully read the instructions, and take the correct way to test, in order to ensure the accuracy of the test results.