FDA Says Rapid Tests at Home Have ‘Reduced Sensitivity’ for Omicron

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Now that the American capacity for COVID-19 testing has been overwhelmed by Omicron, it’s a bit of an inopportune time for the Food and Drug Administration to acknowledge that many of the tests people are relying on to know if they have the virus may not be so helpful at detecting the more transmissible variant. According to a warning issued on Tuesday, at-home rapid antigen tests have a “reduced sensitivity” for finding Omicron, confirming the suspicion of countless people who reported testing negative repeatedly during the Omicron wave, even when they were exhibiting symptoms.

The announcement was made after preliminary studies by the National Institutes of Health’s Rapid Acceleration of Diagnostics found that antigen tests are still able to detect Omicron in samples containing live virus, but are not as reliable as they had been with other strains of the virus.

While rapid tests have always been less accurate than molecular PCR tests, many Americans have relied on them for their convenience to determine if they’re at risk of spreading the virus. With the apparent decline in efficacy, the FDA advises that the public “closely follow the tests’ instructions” by administering two consecutive tests over a period of time, as directed, rather than relying on a one-off negative. Regulators also said people should seek out a PCR test if they are symptomatic or have a “high likelihood of infection due to exposure.”

The FDA warning on Tuesday is one of several changes instituted by public-health officials in recent weeks as the nation struggles to figure out how to manage the latest wave of the pandemic; just last week, a different NIH study showed that antigen tests could detect Omicron “with similar” performance to other strains of the virus. On Monday, the Centers for Disease Control cut the quarantine period for those who tested positive but are asymptomatic to five days, acknowledging that less severe cases associated with Omicron do not require ten days of isolation.

The FDA’s adjusted expectations for antigen tests is not great news for a White House that is already playing catch-up with the latest virus strain. Last week, President Joe Biden announced that the federal government would purchase 500 million antigen tests, though it could take weeks for the order to go through. With the decreased efficacy of the at-home antigen tests, a whole lot more may be needed.