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Antigen Detection

The US Food and Drug Administration has issued an Emergency Use Authorization to Quidel for its SARS-CoV-2 antigen test, as 360Dx reports. This test, it notes, is the first protein-based antigen test to receive such FDA authorization, as other authorized tests are molecular or serology tests.

The rapid point-of-care test, called Quidel's Sofia 2 SARS Antigen FIA, detects nucleocapsid protein antigens from the virus from within nasopharyngeal and nasal swab specimens. The Wall Street Journal adds that Quidel typically develops tests to detect the flu or strep infections and that its tests can be run quickly, within a matter of minutes to determine if a patient has a SARS-CoV-2 infection. "We want to be able to test people quickly," Douglas Bryant, the chief executive of Quidel, tells the Journal. "We want people to be able to get a test at an urgent-care center or a retail clinic."

Such tests could help increase viral testing in the US, which the Journal notes is occurring at a lower rate than experts say is needed to reopen the country.

NPR points out, though, that antigen testing has its drawbacks, as such tests tend to have high specificity but lower sensitivity than that of PCR tests. "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," the FDA says, according to NPR.