Antigen test generally refers to the new coronavirus antigen test, the line is very shallow may be a weak positive result, or it may be caused by operational errors or reagents have been invalidated. 1. Weakly positive result: If the antigen test is performed and the quality control line shows clear color, but the test line is very shallow, it may be due to the low titer of the antigen in the organism, and the result shown is weakly positive. 2. Operational errors: the test line of antigen test is very shallow, it may also be in the test process is not in accordance with the norms of operation, the result of operational errors. 3. Reagent failure: the test line of antigen detection is very shallow, it may also be the problem of the reagent itself, such as reagent expiration or reagent failure. Components in the reagent due to failure can not correctly detect the antigen titer in the specimen, there will also be antigen test line color is very light phenomenon. The antigen test line is very light in color. In addition to the normal weak positive result, as well as operator error, reagent failure, etc., there may be other reasons, and it is recommended to take the test again or to seek the help of your doctor, who will make a judgment based on the actual situation.