FDA Grants Emergency-Use Status for First Coronavirus Antigen Test. The Wall Street Journal May 9, 2020 3:51PM ET by Thomas M. Burton
FDA granted Quidel Corp. of San Diego Emergency Use Authorization for its COVID-19 Antigen test. Unlike molecular tests recognizing the COVID-19 RNA, this test detects nucleocapsid antigens from the COVID-19 virus typically detectable during the acute phase of infection. Antigen tests are common with Hepatitis B Surface Antigen being an example and they can help make the diagnosis of an acute viral infection. The new test is 85% sensitive for detecting COVID-19 from nasal swab or nasopharyngeal swab specimens which are processed, analyzed and rapidly reported on Quidel's SOFIA-2 analyzer. Quidel claims an installed SOFIA base of 36,000 and believes it will ramp up to 1,000,000 tests/week soon. There are over 500,000 laboratories in America most of which are located in physician offices with about 5,000 hospital and 5,000 commercial laboratories.
Antigen methods are less expensive, easier to perform and more scable than PCR-based testing for COVID-19.
Notes from the Instructions for Use (Quidel Corp. San Diego)
Test can be performed in a Waived, Moderate or High Complexity laboratory. Swabs are mixed with reagents that release the viral nucleocapsid and other antigens. A portion of the solution containing the antigens is placed on a lateral flow cassette. As the solution wicks antigens, if present, are captured by monoclonal anti-nucleocapsid antibodies at a specific location. This site is then interrogated by the Sofia-2 device for the presence or absence of the nucleocapsid antigen/antibody complex. A positive test indicates the presence of SARS-CoV or SARS-CoV-2 (The test is not specific for SARS-CoV-2). A negative test should be followed with a PCR-based test if needed. All tests should be used in conjuction with clinical impression.