At-home defense: why widespread rapid antigen testing is key to curbing the pandemic

December 9, 2021, 10:06 PM UTC

Much like in 2020, holiday travel this year is riddled with uncertainty—and the unanswered questions about Omicron don’t make planning any easier. This year, however, one difference could help make travel slightly less fraught: Rapid at-home COVID tests are finally available.

The accessibility—and reliability—of at-home tests have come a long way since the early days of the pandemic, when those available on the market were largely unregulated by the Food and Drug Administration. In December 2020, the agency issued its first emergency use authorization for an over-the-counter at-home antigen test—the Ellume COVID-19 Home Test—and has since approved a handful more, including Quidel’s QuickVue, Abbott’s BinaxNOW, and ACON Laboratories’ Flowflex.

These tests, said Harvard epidemiologist Stephen Kissler, will be useful in light of the recent changes to the CDC’s guidelines for international travel, which require people to have a negative test result within 24 hours of flying into the US. “I think the rapid antigen tests are very good for that,” he said.

He added that they’d be useful as a “screening method” before any large gathering, like a holiday party or family dinner. “I would encourage everyone who’s attending to take a rapid antigen test beforehand,” he said. While PCR tests remain the gold standard for accuracy, often by the time the results come back, enough time has passed that a person may have become newly infected or an infection that previously went under the radar may have become detectable. “For the rapid tests,” he said, “test as close as you can to the thing that you’re testing for.”

Unlike PCR testing, which amplifies the virus’ genetic material so it can detect even tiny amounts, antigen tests look for proteins on the virus surface. One upside of this is that these tests give results more quickly than PCR tests—often in less than an hour—but a downside is that they’re not as sensitive, which means they are more likely to turn up a false negative result. However, as the New York Times noted, antigen tests are “excellent at flagging people who have high viral loads—and who are thus most likely to be actively transmitting the virus to others.”

The rapid tests that are currently available have “pretty comparable sensitivity and specificity,” Kissler said. (Specificity, a test’s ability to tell whether a person is negative for a disease, is similarly high in both antigen and PCR tests.) The major differences between brands are ease of use and the amount of time it takes to turn around a result, he said.

Some public health experts have been calling for widespread at-home rapid testing since the beginning of the pandemic, arguing that they were the key to reopening society. Now, these tests are available in many stores and pharmacies, but there’s still a lot of room for improvement: Tests are often in short supply, and both authorization and manufacturing of additional tests has been sluggish, despite the Biden administration’s September injection of $3 billion in funding into the effort to scale up at-home testing. The administration recently laid out a plan to make tests free to citizens—they generally range from $15 to $35—but the plan drew criticism because it requires people to submit their receipts to private insurers for reimbursement.

Despite the caveats, at-home rapid tests are an important tool for curbing the pandemic. This holiday season, test often and before going to large events, if you can. Doing so can help you avoid unwittingly spreading the coronavirus to large groups of people. “That’s really the fuel of the fire for this pandemic,” said Kissler. Antigen tests “don’t bring the risk of bringing infection to a gathering down to zero, but they do reduce the odds by an awful lot.”

Thanks for reading, and please reach out if you have any questions or comments—I’d love to hear from you.

Stay safe out there,




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