The FDA has granted an emergency use authorization to the Sofia 2 SARS Antigen Fluorescent Immunoassay (FIA) for diagnosing the coronavirus. The test is manufactured by the Quidel Corporation of San Diego, California, and is the first FDA-approved antigen test for the coronavirus.
Unlike standard coronavirus tests that utilize a polymerase chain reaction (PCR) to detect the presence of viral RNA, antigen tests work by quickly identifying any surface fragments of the virus in a sample. The newly approved antigen test will rely on specimens collected from nasal swabs. One of the main advantages of an antigen test is its speed. The Sofia 2 SARS Antigen FIA test claims to take 15 minutes to diagnose the virus.
Although antigen tests are accurate in detecting positive infections, the nature of the test – which requires a high enough presence of the surface proteins to be detectable – means they have a higher chance of false negatives than PCR tests. Results may need to be verified with the slower but more accurate PCR test.
Still, the speed and ease of use of antigen tests may help get daily coronavirus screening in the U.S. to the level needed to reopen the economy.
“I am very enthusiastic about antigen testing because of its ability to be scaled up to millions of tests a day, and because it has a much more rapid turnaround,” said Ashish Jha, MD, Director of the Harvard Global Health Institute.
The FDA expects to grant emergency authorizations for other antigen tests in the near future.