The antigen test is generally referred to as the new crown antigen test, which shows a bar of light color for a variety of reasons. There are mainly the following possibilities: 1. Normal phenomenon: Generally speaking, a light color in the c-zone is a normal phenomenon. When the test is performed, the C zone begins to have color indicating that the test paper used for the test has begun to react. If lines appear in both the “C” and “T” positions, it indicates a positive test. At this time, regardless of whether the color of the “C” area is dark or light, further nucleic acid testing is needed immediately to confirm whether the new crown is infected. In this case, regardless of whether the color of the “C” area is dark or light, further nucleic acid testing is required to confirm whether the new crown is infected. If only the “C” area has a line, then it is negative, and the color of the line in the “C” area is light, which may be normal. 2. Invalid test: If only the “T” line is present and the line is light in color, the test is invalid and needs to be repeated.