The overall redness of the antigen test should indicate a test error and a retest is needed. Antigen test swabs generally appear two results, one is negative, one is positive, negative results are mainly manifested in the T area of a bar, positive results can be manifested in the T area and C area of a bar each. So if the antigen test appears the whole test paper reddish this means that the test has deviated, is not reference meaning, need to be re-tested or go to the hospital under the guidance of the doctor to carry out the test. At present, during the new crown epidemic, the antigen test of the new crown virus can be detected at home by oneself, and can be used for high-risk patients with close contact. It may be inaccurate if not done properly and is best used according to the instructions.