A rapid antigen test (RAT), or rapid test, is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. It is commonly used for the detection of SARS-CoV-2, the virus that causes COVID-19. Rapid tests are a type of lateral flow tests that detect protein, distinguishing it from other medical tests that detect antibodies (antibody tests) or nucleic acid (nucleic acid tests), of either laboratory or point-of-care types.