Can you trust at-home COVID tests? We asked doctors when they’d use them
(NEXSTAR) – As holiday travel kicks into high gear, many are relying on at-home COVID testing kits to help them know if it’s safe to gather with friends and family. But after two million of them were recalled over accuracy issues, you may be wondering if the at-home route is reliable.
First and foremost, the accuracy of the test depends on your ability to follow instructions, says Dr. Jaquelin Dudley at the University of Texas. Most of the tests come with very specific step-by-step instructions – and you should follow them. Make sure you’re swabbing both nostrils for the appropriate amount of time and waiting 15 minutes to see the results.
When used properly, the at-home antigen tests catch about 85% of COVID cases, reports the New York Times. They’re better at detecting COVID cases when someone is symptomatic (and therefore has a higher viral load) than someone who is asymptomatic and has a lower viral load.
The sensitivity to COVID-19 presence won’t be as high as a PCR test sent to a lab, but that may be OK for your purposes. Dr. Bob Wachter, chair of the Department of Medicine at the University of California, San Francisco, says he’s a fan of the rapid tests you can find at your local pharmacy, such as BinaxNOW.
“The situation they excel in is one that frequently arises at holidays: you want to know whether an individual not only has COVID but is actively infectious.” explains Dr. Bob Wachter, “A positive test is very good evidence that the person is infectious; a negative test is quite reassuring that they are not.
“This is the test I want to use in that situation – the PCR just takes too long (often days) and is actually more sensitive than you need. It can detect virus at a level so low that the person isn’t infectious.”
Another thing to keep in mind is that a test result – whether it’s from an antigen test or a PCR test – is just a snapshot in time. It only shows a positive result if the virus is detectable in your system at the moment the sample was taken. That means you need to use rapid tests regularly to be sure you’re not infected and/or contagious.
“If I was gathering with eight fully vaccinated and (if appropriate) boosted people, and I trusted that any of them would bow out if they had any symptoms, I wouldn’t use [a rapid test],” says Wachter, as the risk of asymptomatic COVID-19 transmission between fully vaccinated people is very low.
“But if one of the people was not vaccinated, I’d insist that he or she do a rapid test that day and could only come in if negative,” he continues. “I might do the same if someone was vaccinated more than six months ago and hadn’t yet been boosted. And I’d certainly have anyone with a runny nose or any potential COVID symptoms test before being let into the gathering.”
Dudley, on the other hand, still prefers to get a PCR test wherever available. If you are relying on rapid testing, she suggests doing your research on the manufacturer to make sure it’s a reputable brand.
“The user should look for information about how the test has been verified. If you can’t tell, ask the pharmacist to help you choose the test,” says Dudley.
Also, if you’re feeling sick, Dudley suggests following any sort of rapid test with a PCR test to confirm the results. In the meantime, you should also stay away from others and contact your doctor.