But the first so-called antigen test — announced Saturday by the Food and Drug Administration — is not quite the kind sought by top government health officials. WHY IS ANTIGEN TESTING IMPORTANT? The new test uses a nasal swab like other screening tests, and delivers results in about 15 minutes. OraSure Technologies has a $710,000 federal contract to develop a saliva-based antigen test that could be performed at home. The company has antigen tests for other viruses — including HIV and Ebola — and those have accuracy rates of over 95%.