Antigen test generally refers to the new coronavirus antigen test, one dark and one light suggests that the new coronavirus antigen test is positive, it is recommended to “stand still” and contact the hospital and community in time to close the loop to the hospital for further testing and diagnosis. There are three letters on the antigen test kit, C, T and S. S represents the spiking area, C is the quality control area on the test paper and T is the detection area, C shows whether the reagent is valid or not, while T shows whether it is positive or not. Generally speaking, there are 3 possible results positive, negative and invalid after the test. 1. Negative result: “C” shows a red or purple color band and “T” shows no band. 2. Invalid result: no red or purple band is shown at “C”, regardless of whether the band is shown at “T” or not. The result is invalid and the test strip should be retaken and retested. 3. Positive result: When both “C” and “T” show red or purple bands, the color of the band at “T” can be dark or light, all are positive results. At this point, you should remain still, wear a mask, and contact the hospital and community in a timely manner to close the loop and go to the hospital for further nucleic acid testing in order to make a clear diagnosis.