The Wrong Way to Test Yourself for the Coronavirus


Rapid tests can help you stay safe in the Delta outbreak. But you have to use them correctly.


In mid-June, Joanna Dreifus hit a pandemic milestone. The final member of her household—her teenage son—reached the point of full vaccination. “We had about two weeks where I thought, Phew, we’re okay,” Dreifus, a special-needs-education consultant in New York City, told me. Then the Delta variant took over. By July Fourth weekend, murmurs of post-vaccination infections, though uncommon, were starting to trickle into her social-media feeds. “I knew I’d need to stock up on more tests,” Dreifus said.

She estimates that she’s now using at-home antigen tests—the over-the-counter ones that return results in minutes—to screen her family for the coronavirus about three times a month. She pulls them out when anyone feels a sniffle coming on, or when she and her kids, 15 and 18, are about to visit her elderly, vaccinated parents. Dreifus knows the vaccines are still doing their part, but “Delta has basically taken us back to many of our pre-vaccination precautions,” she told me. Combined with masking, distancing, and socializing mostly outdoors, tests bring her extra peace of mind.

Dreifus’s decision turned out to be prescient. In early July, the CDC was still insisting that fully vaccinated people didn’t need to mask indoors, or seek out tests after virus exposures if they didn’t have symptoms—guidelines that hinged on the assumption that vaccinated people were almost never getting infected. By month’s end, spurred by Delta’s rise, the agency rolled those recommendations back. Vaccines clearly still curb a person’s chances of catching the coronavirus and passing it on. But they can’t stave off those outcomes completely, especially in the parts of the United States where the super-transmissible variant is running rampant. Right now, that’s just about everywhere.



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