MAy 9, 2020 - The FDA has issued the first emergency use authorization for a COVID-19 antigen test, which is a new type of test that detects virus proteins. It is a diagnostic test that indicates whether someone has the coronavirus at the moment. Samples are taken with a nasal swab.
The authorization was issued late Friday to Quidel Corporation, the FDA said in a news release on Saturday. The test will be available for both point-of-care testing and high capacity labs.
The antigen test differs from the other two tests currently available, which include a polymerase chain reaction (PCR) test and a serological test. The PCR uses a nasal swab and detects genetic material from the coronavirus to diagnose an active COVID-19 infection. The serological test uses a blood sample and detects antibodies to the virus to identify people who developed an immune response.
The new antigen test is a diagnostic tool like the PCR test, but instead of looking for the genetic sequence of the coronavirus, it looks for antigens, or molecules on the surface of the virus.
On the positive side, antigen tests can be run quickly and may produce results within minutes. On the negative side, antigen tests may not detect everything or be as “sensitive.” Positive results tend to be accurate, but the tests can have a higher number of false negatives.
The Quidel test is 85 percent sensitive, or able to correctly identify patient samples with the coronavirus, according to the Wall Street Journal.
“Negative results do not rule out infection,” according to the FDA statement. “With this in mind, negative results from an antigen test may need to be confirmed with a PCR test.”
Despite the drawbacks, antigen tests are important for the overall COVID-19 response, the FDA says, because they’re simple and cheap to make and can be produced by multiple manufacturers. This type of test has the potential to scale to millions of tests per day.
This development could “better identify infection rates closer to real time,” the statement said.
The FDA expects to authorize more antigen tests. The agency will also create a template for antigen tests to speed up the review process for emergency use authorizations.