At-Home COVID and COVID/Flu Tests: Where to Buy and What You Should Know

Molecular tests conducted in labs — the most well-known type being a PCR (polymerase chain reaction) test — are still considered the gold standard for confirming or ruling out a COVID-19 infection. But even though most at-home tests are not as sensitive as lab tests, they can quickly detect the existence of “a level of the virus that we have to be concerned that somebody could transmit [COVID-19] to someone else,” said Clare Rock, an assistant professor at Johns Hopkins University School of Medicine who ran a COVID-19 infection-control consultancy.

A negative at-home result, however, doesn’t necessarily mean that someone doesn’t have COVID-19. For instance, if you swab too soon after a potential exposure, you may test negative even if you are carrying the virus. Per the CDC, to rule out potential COVID infection, the FDA recommends “2 negative antigen tests for individuals with symptoms or 3 antigen tests for those without symptoms, performed 48 hours apart.”

“Serial testing boosts sensitivity,” said Christopher Brooke, an infectious-disease expert at the University of Illinois at Urbana-Champaign. “The odds that you’re going to test negative twice when you’re infected are much lower than the odds that you’re going to test negative once.”

Although PCR tests are known to be so sensitive that they can detect a weeks-old COVID-19 infection (even after the person is no longer infectious), that isn’t the case for at-home rapid antigen tests. If you test positive with a rapid antigen test, you’re quite possibly still infectious. “If you’re positive, you’re positive,” said Wilbur Lam, a professor of pediatrics and biomedical engineering at Emory and the Georgia Institute of Technology and a clinical pediatric hematologist at Children’s Healthcare of Atlanta.

In November 2023, the Acon Flowflex COVID-19 Antigen Home Test became the first at-home rapid antigen test cleared through the Food and Drug Administration’s traditional premarket review process. Many more have since earned the same clearance. Altogether, more than six dozen rapid antigen tests have earned FDA clearance or emergency use authorization (EUA) for at-home use without a prescription. These include COVID-19 tests and COVID/flu combination tests.

The accuracy of an at-home antigen test depends in part on test sensitivity (in a nutshell, the test’s reported ability to detect a true positive), test specificity (its reported ability to detect a true negative), sample integrity (whether a swab contains enough sample or the swab solution is contaminated by, say, another pathogen), whether the person follows the manufacturer’s instructions exactly, the time since the person’s last known or suspected exposure or their onset of symptoms, and the person’s viral load at the time of testing.

In general, these tests all have about the same ability to detect the virus, and you should feel comfortable using any of them to check for a COVID or flu infection, said Michael Mina, a former Harvard epidemiologist.

For a test to be FDA-cleared (or considered for emergency use authorization), test makers must submit to the agency clinical data demonstrating test sensitivity and specificity. Note that these sensitivity and specificity percentages are a snapshot in time, with a limited sample. (Some independent studies have shown much lower sensitivity for some antigen tests, particularly when they’re used on asymptomatic individuals.) “Most of these tests do work, but there is no such thing as a perfect test that works 100% of the time,” said Lam, whose team helped test rapid antigen tests on behalf of the National Institutes of Health.

At-home COVID and COVID/flu tests are authorized for use on people as young as 2 years old, provided that any child’s sample is obtained and processed by an adult. The instructions that accompany all of the tests listed below also include a disclaimer indicating that negative results may require additional testing for confirmation. For each of them, there is a small, lesser chance of false-positive results, too.