The US FDA has authorized the first COVID-19 antigen test, a new category of tests for use in the ongoing pandemic. Antigen diagnostic tests quickly detect fragments of proteins found on or within the virus by testing samples collected from the nasal cavity using swabs.

The emergency use authorization was issued for the Sofia 2 SARS Antigen FIA, manufactured by Quidel Corp and authorized for use in high and moderate complexity CLIA laboratories and point-of-care testing by facilities operating under a CLIA Certificate of Waiver.

According to the FDA, antigen tests can provide results in minutes, but may not detect all active infections. “This means 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. With 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,” the FDA said in a statement.

Antigen tests are different than the two other types of diagnostics being used for COVID-19: molecular PCR tests that detect active COVID-19 infections, and serological tests that look for viral antibodies post-infection.

“Antigen tests are also 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 Americans per day due to their simpler design, helping our country better identify infection rates closer to real time.

“This is just the first antigen test to be authorized and we expect more to follow.”