If a vertical bar appears in the antigen test, then it means that the test result is wrong. Generally the antigen kit will show two results, one is the T-zone and C-zone, a horizontal line appears at the same time, this kind of result is positive. If only the T-zone shows a horizontal line, then the result is negative. Other results, such as a horizontal line in the C-zone only, a vertical line, or a reddish coloration in all areas of the test strip, are generally considered to be a test error. In your case, the vertical bar is generally a detection error, and you need to retest or go to the hospital for further examination. It is recommended that you follow the instructions strictly to avoid erroneous test results.