Dozens of different at-home COVID-19 tests are now available from big-box retailers and pharmacies, having secured emergency use authorization from the Food and Drug Administration.
Some of the tests are only available by prescription, while others can be purchased over the counter. According to the Centers for Disease Control and Prevention, the tests use either a nasal or saliva sample, which is then sent to a testing lab for results or analyzed by the consumer.
But before you run out and buy one, a few words of caution.
“Home tests are not 100%,” said Dr. Emily Landon, an infectious disease specialist at UChicago Medicine. “This is not like a pregnancy test where you take it and you’re good to go.”
There are several different types of COVID-19 tests, but Landon favors polymerase chain reaction (PCR) tests because they are “the most sensitive.”
“They’re able to detect COVID even in really low viral situations – individuals that are at the very, very beginning of infection … or people who are vaccinated who have a really mild, asymptomatic infection,” Landon said.
While Landon advises people to visit a testing site or their doctor for a free COVID-19 test (at-home kits can range from $20-$100), she understands the appeal of DIY tests for people with limited mobility or transportation options.
“I’m always going to recommend you go to a doctor for a test. Unless you can’t get a test any other way, then you could use one of these home tests,” Landon said.
If you do buy an at-home test, she recommends buying a PCR-based test and following the directions “as best you possibly can.”
However, there are a few groups who should steer clear of any at-home test, according to Landon.
“If you’re a vaccinated person who’s asymptomatic, there’s no reason to be doing at-home COVID testing,” she said. “If you develop symptoms, you need to go and get a good test to make sure you don’t have COVID.”
Similarly, at-home tests for people who are asymptomatic but not vaccinated “are not likely to give you a good result or a true result. You could still have COVID,” Landon said, adding that at-home tests include disclaimers stating they can’t detect COVID-19 when viral loads are very low.
She also doubts that results from at-home tests will suffice for summer events that limit entry to people who are fully vaccinated or have recorded a negative COVID-19 test within 24 hours of arriving, like Lollapalooza, which returns to Grant Park at the end of July.
“I suspect you’ll have to go to a COVID testing place and get an official medical test as opposed to an at-home test,” Landon said.
But for those still set on trying an at-home option, Landon suggests timing your test to account for possible COVID-19 exposures.
“The incubation period for COVID is 2-10 days, so if you’re unvaccinated against COVID and you have an exposure anytime in the past 10 days, you could have a positive COVID test,” Landon said. “But you could also not have a positive COVID test for another few days and still have COVID.”
Because testing too early can result in a false negative, Landon encourages people to isolate themselves before using an at-home test.
“If you do a stay-at-home watching period, where you don’t have any exposure for five to seven days before you take that test, that test is going to better reflect what happened in the days before,” she said.
As for at-home test results, “if you get a positive COVID test, chances are pretty good that you have COVID. But sometimes you can see false positives,” Landon said, adding that if you’re asymptomatic and test positive, you should see your doctor.
“If you’re symptomatic and you get a negative test on one of these tests, you should still self-isolate. All the tests say that in their paperwork and you should follow that to see how you do,” she said. “If your symptoms continue or if you have loss of smell or taste, which is pretty specific for COVID, or if you get sicker, you shouldn’t assume you didn’t have COVID. That test can be falsely negative. Either repeat the test, use a different kind of test or, better yet, go to a doctor and get a COVID test at a COVID testing site.”
Ultimately, the best option is to get vaccinated, Landon says.
“Testing doesn’t prevent COVID. It just identifies it once it’s there. And so right now, the best thing you can do is get vaccinated,” Landon said. “Anybody who’s thinking about using a test to protect themselves – that’s the wrong way to look at it.”