People often talk about COVID-19 testing like it means only one thing. But in reality, the U.S. Food and Drug Administration (FDA) has so far granted emergency-use authorization to more than 200 different tests meant to detect a current or past infection from SARS-CoV-2, the virus that causes COVID-19. Most recently, the agency made headlines for approving the first such test that uses saliva samples, the aptly named SalivaDirect test out of the Yale School of Public Health.
These COVID-19 tests fall into three main categories: PCR, antigen and antibody. Dr. Aneesh Mehta, chief of infectious diseases services at Emory University Hospital in Atlanta, Ga., broke down the differences between them—and what to keep in mind if you decide to get tested.
The majority of COVID-19 testing happening in the U.S. right now uses polymerase chain reaction (PCR) technology. These tests detect disease by looking for traces of the virus’ genetic material on a sample most often collected via a nose or throat swab. The U.S. Centers for Disease Control and Prevention (CDC) considers PCR tests the “gold standard” of COVID-19 testing, but, like all tests, they’re not perfect. Studies have suggested as many as 30% of COVID-19 PCR test results are inaccurate. (For comparison, the CDC in 2018 estimated that rapid flu tests have about the same rate of incorrect results.)
With COVID-19 tests, false negatives seem to be much more common than false positives—so if you get a positive result, you very likely do have the virus. If you get a negative result but have coronavirus symptoms or recently encountered someone sick with the virus, you should still self-isolate until symptoms subside…