Rapid COVID Tests May Be Less Accurate with Omicron, the FDA Warns

Some rapid antigen tests may be less effective in identifying early strains of Omicron.

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There's a lot we still don't know about the latest COVID-19 variant, but according to the Food and Drug Administration's (FDA) latest advisory, some rapid antigen tests may be less effective in identifying early strains of Omicron.

On Tuesday, the FDA cited preliminary studies—conducted in partnership with the National Institutes of Health (NIH)—that analyzed how at-home tests performed in identifying the Omicron variant. The agency found that some of these tests were less sensitive in detecting Omicron due to its heavily mutated nature.

The FDA said that "early data suggest that antigen tests do detect the omicron variant but may have reduced sensitivity."

In other words, these tests could present false negatives by missing present omicron infections.

"They're not picking up infections as early as previous versions,” Gigi Gronvall, senior researcher at the Johns Hopkins Center for Health Security, told NBC News. She suggests that anyone who feels symptomatic should isolate a little while longer and take the test again.

The FDA has not ruled out rapid antigen testing altogether and did not identify which test producers were used in the sample.

"The FDA continues to authorize the use of these tests as directed in the authorized labeling and individuals should continue to use them in accordance with the instructions included with the tests," the agency said in a statement. "Antigen tests are generally less sensitive and less likely to pick up very early infections compared to molecular tests."

Rather, the FDA is advising follow-up PCR tests for those that test negative with a rapid antigen test but are experiencing symptoms. Those that test positive, according to the FDA, should "self-isolate and seek follow-up care with a health care provider to determine the next steps."

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Megan Schaltegger is a staff writer at Thrillist.