An antigen test is a diagnostic test that checks to see if you're infected with the coronavirus. The test looks for proteins (antigens) in a sample taken from your nose or throat. Antigen tests are faster than PCR tests. COVID19AgLTFLOW Antigen Test Kit (Colloidal Gold) is an in vitro immunoassay. The assay is for the direct and qualitative detection of antigen of SARS-CoV-2 from nasopharyngeal secretions,oropharyngeal secretions specimens . The kit is for in vitro diagnostic use.