Is it normal for an antigen test to show only one line?

　　The term "antigen" may refer to the SARS-CoV-2 antigen test. Generally, whether a single line in a SARS-CoV-2 antigen test is normal depends on the location where the line appears. A line appearing in the C region is considered normal, whereas a line appearing only in the T region is abnormal. Detailed analysis is as follows:

　　1. Normal: Antigen test kits are primarily used to detect whether an individual has been infected with the novel coronavirus. The test strip contains two regions: the C region (control line) and the T region (test line). If a line appears only in the C region, the result is negative, indicating no infection with the novel coronavirus, which is considered normal.

　　2. Abnormal: If a line appears only in the T region and not in the C region, the test result is invalid. This could be due to sample contamination, expired or faulty test reagents, or improper testing procedures. It is recommended to repeat the test with a new antigen test kit. If both C and T regions show lines (two lines), the result is typically positive, indicating possible infection with the novel coronavirus.

　　The novel coronavirus mainly spreads through respiratory droplets. Infected individuals may develop symptoms such as fever and cough. Under medical guidance, medications like ibuprofen tablets, Powerful Loquat Syrup, or Chuanbei Cough Relief Syrup may be used for treatment. Wearing a mask when going out is advised to prevent spreading the virus to others. Drinking plenty of warm water and maintaining adequate rest can also help support recovery.