The U.S. Food and Drug Administration has issued the first Emergency Use Authorization (EUA) for a COVID-19 antigen test,
a new category of tests for use in the ongoing pandemic. These diagnostic tests can be useful for the quick detection of
fragments of proteins found on or within the virus by testing samples collected from the nasal cavity using swabs. This
test is authorized for use in high and moderate complexity laboratories certified by Clinical Laboratory Improvement Amendments
(CLIA), as well as for point-of-care testing by facilities operating under a CLIA Certificate of Waiver.
Antigen tests are important in the overall response against COVID-19 as they can generally be produced at a lower cost than
PCR tests and once multiple manufacturers enter the market, can potentially scale to test millions of people per day due to
their simpler design.
However, antigen tests may not detect all active infections, as they do not work the same way as a PCR test. Antigen tests
are very specific for the virus but are not as sensitive as molecular PCR tests. This indicates that positive results from
antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection.
Keeping this in mind, negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment
decisions or to prevent the possible spread of the virus due to a false negative.