Antigen tests are immunoassays that detect the presence of a specific viral antigen, which implies current viral infection. Antigen tests are currently authorized to be performed on nasopharyngeal or nasal swab specimens placed directly into the assay's extraction buffer or reagent.

How accurate is COVID-19 rapid antigen testing?

One small study found that antigen testing every three days is 98 percent accurate at detecting SARS-CoV-2 infections, but there is no magic number for how often concerned individuals should take these tests, experts say. People who test positive (or “detected”) should take the result seriously and seek health care.

How accurate are at-home COVID-19 antigen tests?

Some of the at-home antigen tests have an overall sensitivity of roughly 85 percent, which means that they are catching roughly 85 percent of people who are infected with the virus and missing 15 percent.