Traversing the unknown has always been the scariest part of the pandemic. Is Covid an unseen guest at the dinner party? Did Covid catch a ride home with us from our recent trip? Is that sluggish feeling due to a bad night’s sleep—or is it an early sign of infection?
Those questions are becoming much easier to answer, thanks to a flood of at-home Covid tests that are free of charge. Four metro Atlanta counties (DeKalb, Fulton, Cobb and Clayton) have distributed thousands of free tests. The Biden Administration is mailing out four free tests per household, which can be ordered at covidtests.gov. And a new federal rule requires private health insurers to cover eight tests per month per person, although you might have to buy them first and file for reimbursement. (Traditional Medicare does not cover the at-home tests, although some Medicare Advantage plans might.)
The exact mechanics of the tests vary, but they share some essential elements. You swab both nostrils, soak the swab in a chemical reagent and wait for a line or lines to appear on a card or strip. It usually takes about 15 minutes to get a result.
“If you’re positive, there’s virus in your nose and the likelihood that you’re infectious is pretty high,” says Wilbur Lam, an Emory University pediatric hematologist/oncologist and Georgia Tech bioengineer who directs the Atlanta Center for Microsystems Engineered Point-of-Care Technologies, a joint program of Emory, Georgia Tech and Children’s Healthcare of Atlanta.
At the start of the pandemic, the National Institutes of Health tapped the center to analyze proposed at-home tests for faster authorization by the Food and Drug Administration. They studied about 100 proposed tests and gave a green light to more than a dozen different brands, which are now available at pharmacies and stores.
As they look for the limits of detection, the analysis uses smaller and smaller concentrations of virus, says Lam, who co-directs the center with Oliver Brand, a microsystems engineer at Georgia Tech, and Greg Martin, a clinical pulmonologist at Emory. A usability group tests how likely users are to follow the steps properly.
Atlantans also are helping shape national testing strategies through other Covid studies. Last fall Say Yes! COVID Test, a National Institutes of Health study in eight communities around the country, gave bundles of eight at-home tests to residents of South Fulton—a give-away of 410,000 tests. In a subsequent survey, most people reported that the tests were easy to use and that they planned to use them to protect themselves, their families and their community from transmission. The study hasn’t yet determined if at-home testing reduces community-wide Covid spread.
Morehouse School of Medicine is a site of another NIH study, Covid-19 Test Us, which asks participants to take two nasal swabs periodically over two weeks—to compare at-home test results with the standard lab test known as PCR.
Meanwhile, the rest of us will have to figure out our own strategies for using a few of the billion at-home Covid tests being purchased by the Biden Administration. NIH created a When to Test online calculator to help. To parse the decision-making, we asked for guidance from some experts:
Will the tests show I’m infected even if I don’t have symptoms?
Yes, but not perfectly. The at-home antigen tests contain antibodies that attach to pieces of the virus, and you need to have enough of the virus particles in your nose for the swab to pick it up. (There’s no need to stick the swab way up in your nasal cavity, as was done early in the pandemic, Lam says.) The at-home tests are packaged in sets of two so you can take a second test a day or two later. If you’re still negative, then you can feel more certain of the result, he says.
Do the at-home tests miss some infections?
While false positives are very rare, as many as 20 percent of negative results are actually missed infections. You can be infectious up to three days before developing symptoms, according to the Centers for Disease Control and Prevention, and the rapid test might not pick up the virus at that early stage. The PCR test, conducted by a lab to detect viral RNA, provides more certainty—if you can wait one to three days for a result.
Is it safe to gather indoors with friends if we all test first?
Although the tests aren’t perfect, they can add some protection, especially if everyone tests twice—a day or two before the gathering and just before getting together, advises Harry Heiman, a family medicine physician and clinical associate professor at Georgia State University’s School of Public Health. “If you’re going to do one test, do it as close to when you’re going to have an interaction with a person as possible,” he says.
Can I use the test to figure out when I’m not infectious anymore?
Yes. The at-home tests will begin showing a negative result even if you previously tested positive and have lingering symptoms. That’s a sign that your infectious period likely has ended, Lam says. PCR tests can’t be used to signal whether you’re still infectious because they can remain positive for weeks or even months after you recover.
Do the tests work with omicron?
Yes. All the tests were reassessed with the current variant. There may be some change in their detection levels and there is variability among different products currently on the market, but all tests still are able to detect omicron infections, Lam says.
Would it work better if I swab my throat instead of my nose?
No. Poking yourself uncomfortably in your throat with the swab isn’t advised, says Lam. He and his colleagues are still exploring this question, but so far they have found that the omicron variant appears in the nose and throat. “These tests were designed, optimized, and FDA-authorized only for nasal swabs,” he says. “There’s no scientific data to justify moving to a throat swab, at least as of right now.”
If you’re infected with omicron, the virus will appear in your nose and your throat. “These tests were optimized for nasal swabs,” he says. “There’s no scientific data to justify moving to a throat swab.”
Can I use the tests on my child?
Yes, based on the age range printed on the test package. Some tests have been validated for children 2 and older. Keep in mind, though: While positive results are definitive, a recent analysis of 17 studies found a high rate of false negative results in rapid antigen tests used with children, especially if they don’t have symptoms.
If I test negative, can I go mask-less?
While taking two tests a day or so apart can give you some comfort that you’re not spreading Covid at an indoor gathering, mask-wearing adds protection, especially if someone is at risk—for example, because they have a serious medical condition or they’re elderly. And a negative test won’t stop you from getting sick if you encounter someone with Covid-19, so masking up is still an important layer of protection, especially in crowded areas and spaces where you don’t know the status of the people around you. “Alone, [tests] are not enough,” says Rachael Fleurence, special assistant for Covid-19 diagnostics to the NIH director and program lead of Say Yes! Covid Test. “They’re extremely valuable when they’re used properly,” but they’re just one tool to prevent infection, she says.
How should I use the tests if I’ve been exposed?
“Test three to five days after that exposure. If the test is negative, with an antigen [at-home] test I would repeat it again in two days,” Heiman says. If you still test negative and have no symptoms, “at that point I would consider myself clear,” he says. If you have symptoms, he advises testing two to three days after they appear. If the result is negative, repeat the test again within a couple of days. Or take a PCR test for a more definitive result, he says.
Are these tests our ticket out of the pandemic?
“Rapid antigen tests for home use are not going to solve the pandemic, but they’re among the many tools that can have an incremental effect on improving things,” Heiman says.
So, not the “silver bullet” we yearn for, but this is another step toward life beyond the pandemic.