SARS-CoV-2 & Influenza A/B Antigen Combo Rapid Test Kit (LFIA) uses a double antibody sandwich method to detect SARS-CoV-2 and Influenza A/B by colloidal gold immunochromatography.

When the appropriate amount of test samples treated with lysis buffer is added to the sample well of the test cassette, the sample will move forward along the test strip by capillary action. If the sample contains SARS-CoV-2 or Influenze A/B virus nucleocapsid antigen, and the concentration is higher than the limit of detection, the antigen will form immune complexes with corresponding Nucleocapsid Protein antibody labeled with colloidal gold respectively, which are captured by N line, A line, or B line. If test sample contains SARS-CoV-2 virus, forming a red N line, indicating a positive result for SARS-CoV-2. If test sample contains Influenza A virus, forming a red A line, indicating a positive result for Influenza A. If test sample contains Influenza B virus, forming a red B line, indicating a positive result for Influenza B.

Additionally, the test strip also contains a control line(C line). The C line should be formed to indicate that the sample has been transported properly through the membrane regardless of whether sample contains antigens or not. If the C line does not appear, it indicates that the test result is invalid and the sample need to retest.