This story has been updated. It was first published on April 28, 2021.
Since the coronavirus pandemic’s earliest days, public health experts have agreed that intercepting and minimizing outbreaks would rely on our ability to answer a seemingly simple question: Do I have the virus?
Getting tested—and tested frequently—has been the mantra for helping slow the spread of COVID-19. With increased traveling during the holiday season and cases of new variants, like Delta and Omicron, on the rise, experts say testing (on top of getting vaccinated) is crucial in keeping infection numbers low. Compared to this time last year, consumers have far more COVID-19 testing options available to them—including a handful of tests that can be administered from the comfort of home.
“Each type of test has its place,” says Patrick Godbey, lab director of Southeast Georgia Regional Health System and Southeastern Pathology Associates. “You use the different types of tests for different situations.” And the advent of do-it-yourself tests, he says, “has the potential to be tremendous.”
Most of the at-home tests authorized by the US Food and Drug Administration to date are kits that ask users to collect their own spit or swab samples and mail them to a lab for processing. But in recent months, the FDA has also granted emergency use to at least 13 at-home tests that return results on the spot, within an hour.
Experts hope the broadening selection of testing options will help prevent people with asymptomatic infections from turning into unwitting super-spreaders. Government officials are also responding to testing needs: Certain states, such as Massachusetts and New Jersey, have created programs to deliver free, rapid tests to residents, while President Biden announced a plan earlier this month that will soon require private health insurers to cover the costs of over-the-counter, at-home COVID tests.
“The three most dangerous words during COVID are ‘I feel fine,’” says Mara Aspinall, co-founder of the biomedical diagnostics program at Arizona State University. “We need to be testing regularly. No test is perfect, and this disease is, unfortunately, sneaky.”
How do at-home rapid COVID-19 tests stack up?
So far, the US has administered more than 682 million COVID-19 diagnostic tests, according to the Centers for Disease Control and Prevention. Many of these tests use a molecular technique called polymerase chain reaction, or PCR, that looks for small pieces of the virus’s genetic material in a sample (usually a swab of the nose or upper throat, but sometimes saliva) taken by a health worker at a testing site.
The accuracy of COVID-19 tests are based on two main factors: Sensitivity and specificity. A test’s sensitivity is how well it can correctly identify a person who has the disease, in this case, COVID-19; a test’s specificity measures how well it identifies those without the disease. The closer each of those are to 100 percent, the more accurate the test.
Because PCR is a lab test, it can take a few hours or days to turn around results. But the technique is highly accurate at picking up positive cases since it can confirm the virus’s genetic presence—even if faint—in a given sample. “It is considered the gold standard,” says Thomas Denny, a professor of medicine at Duke University Medical Center.
Most of the newly-approved at-home kits that return results right away use a different, much faster technique. Instead of looking for traces of the virus’s genetic footprint, these tests—called antigen tests—screen for fragments of proteins shed by the virus.
Antigen tests are good at quickly identifying people with larger amounts of the virus, and therefore, proteins shed by it. These individuals are typically more infectious and should self-quarantine.
However, antigen tests are far less sensitive than PCR tests and are more likely to lead to false negatives—in which the test gives a negative result even though the person has COVID-19—especially in folks who are asymptomatic. Depending on the stage of an infection, it is possible for someone to be negative according to an antigen test but positive with PCR, or vice versa, experts warn. Faulty, unreliable test results have led to major recalls of millions of at-home tests, as was the case earlier this fall, when more than 2 million of Ellume’s home tests were affected by higher-than-acceptable false positive results.
Experts also stress the danger of mishandling at-home tests, since (after all) most of us are not professionally trained to collect saliva, take nasal swabs, or properly store sensitive testing materials.
“You have people who are not used to performing laboratory tests performing those tests,” says Godbey, who also serves as president of the College of American Pathologists. “They need to be meticulous about every aspect.”
And regardless of what type of test you’re taking, there’s always the possibility of picking up the virus right afterward—which makes it nearly impossible to ever conclude with certainty that someone is not infected.
“Testing is only a snapshot of a particular time,” Denny says, “whether you do it at home or at a testing center.”
How easy are at-home tests to use?
Popular Science staff ordered and tested a few of these at-home tests to evaluate their ease-of-use, identify any struggle points, and determine how useful they are for consumers overall.
Ellume
- Availability: Online, over the counter at most major pharmacies
- Ages: 2 years and older
- Cost: $30
- Sensitivity: 82 – 99 percent (95%)
- Specificity: 93 – 99 percent (97%)
DIY Assistant Editor Sandra Gutierrez tried out an antigen test made by Australian manufacturer Ellume, which was the first rapid, fully at-home antigen COVID-19 test authorized by the FDA. The test costs about $30 online and at pharmacies, and delivers results within 15 minutes.
The self-administered nasal swab is just as annoying as when it’s taken by a professional, according to Gutierrez. “If you think that controlling the swab makes it any better,” she says, “it does not.” But overall, Ellume’s testing process was fairly easy.
Update: On October 5, 2021, the FDA recalled more than 2 million Ellume COVID-19 tests due to abnormally high rates of false positive test results in certain affected lots. The issue was categorized as a Class I recall, the FDA’s most serious type of recall, due to the serious health implications of delayed diagnosis of the actual illness or incorrectly administering COVID-19 treatment. Thankfully, none of the users of recalled tests who reported false positive results have died. You can still buy Ellume at-home tests, but the company is maintaining a voluntary recall policy, which allows you to return and replace tests if you believe it was a part of the recall.
Abbott’s BinaxNOW Self-test
- Availability: Over the counter at most major pharmacies
- Ages: 15 and older
- Cost: $24
- Sensitivity: 92 percent (per company); 76 – 90 percent (85%) per FDA.
- Specificity: 100 percent (per company); 96.6 – 99.5 (98.5%) per FDA
Another at-home antigen test, Abbott’s BinaxNOW, promises results within 15 minutes and is available now at major drugstore chains including Walgreens and CVS at $24 per box. Each box comes with two tests; both should be used by the same individual, with the second taken 36 hours after the first. This can help compensate for the typical downside of an antigen test—taking two makes it less likely to miss an infection just because it’s new, especially if you isolate at home in the interim.
DxTerity
- Availability: Amazon and Walmart
- Ages: Adults and children under the age of 18 with adult supervision
- Cost: $99
- Sensitivity: 97.2 percent
- Specificity: 92.5 percent
For those who are willing to quarantine for a few days while waiting for COVID test results, mail-in kits might be a better option. These kits still rely on the user to collect the sample, but the analysis is done in the lab, using the same technique that PCR tests done at a doctor’s office or clinic employ. These tend to be a little more expensive, but they’re also more accurate.
As Science Editor Claire Maldarelli learned, one of these at-home collection kits, from DxTerity, will cost you around $100, doesn’t require a prescription (some kits do), and you can order it on Amazon. The COVID test requires a saliva sample, rather than a nasal swab. It was, however, “extremely easy to use,” she says, with easy-to-follow instructions and clearly-labeled equipment. Her only additional note: “You need a lot more saliva than you realize!”
Labcorp Pixel and Quest Diagnostics
- Availability: Online, over the counter at major pharmacies
- Ages: 2 and older
- Cost: $119 to $125
- Sensitivity: 100 percent (Note that this is not a fully do-it-at-home PCR setup. The sample is processed with a cobas SARS-CoV-2 & influenza A/B Test.)
- Specificity: 100 percent
Another mail-in alternative is Labcorp’s Pixel at-home kit, which runs $119 out of pocket and can be ordered on the company’s website without a prescription. Associate technology editor Rob Verger tried Labcorp’s Pixel kit out, and found its 12-step process fairly painless. He did note that the process requires setting up an account with the company and dropping the test off at a FedEx location in time for a same-day express service—“so you’ll need to fit that step and timing into your plans.”
His verdict: “As easy as a home COVID test could be, it seems, but you still need to devote a little bit of time to doing it carefully.”
Quest Diagnostics
- Availability: Online
- Ages: 2 and older
- Cost: $125, includes health physician fee
- Sensitivity: 100 percent
- Specificity: 100 percent
Quest Diagnostics makes a similar at-home kit to Pixel, priced at about $125, which also gets sent back to the lab for testing. Your test is received and sent to the lab free of charge.
Other at-home COVID-19 tests to consider
Beyond the handful of options tested by Popular Science, a small cadre of new tests offer actual molecular analysis (similar to PCR testing) from home.
Cue
- Availability: Online
- Ages: 2 and older
- Cost: $50 – $90 monthly membership; $225 3-pack
- Sensitivity: 97.4 percent
- Specificity: 99.1 percent
Cue’s at-home testing cartridge looks for the coronavirus’s genetic material, like a lab test, but returns results in about 20 minutes. It is an FDA-authorized at-home molecular test—considered more accurate than the rapid antigen tests. The testing kit uses a nasal “wand” or swab, cartridge, and a square, multi-use reader that connects to a mobile app via Bluetooth. However, Cue’s purchasing options are pricey, which includes a membership model: $50 per month for 10 tests a year and $90 per month for 20 tests a year. You can also do one-time purchases of test packs, starting at $225 for three. But all of these options require you to buy the $249 reader separately (there is a discount on the reader and additional tests if you choose one of the memberships).
Lucira Check It
- Availability: Online at LuciraHealth.com
- Ages: 2 and older
- Costs: $75
- Sensitivity: 94 percent in symptomatic individuals, 90 percent in asymptomatic
- Specificity: 98 percent
The Lucira Check It at-home kit is a cheaper molecular test option. These single-use tests include a AA battery-operated test device, sample vial, and nasal swab. Like PCR tests, they also detect genetic material of the virus, though they use a slightly different method to identify the viral DNA, and turn around positive results in as soon as 11 minutes and 30 minutes for negative results. If you need an official digital record of your results, Lucira can send a free text message to your phone—no app required.
In October 2021, Lucira recalled the swabs included in the kit, which were supplied by a partner company, Copan. The affected kits were distributed between April 22, 2021 through September 22, 2021. These kits should not be used and Lucira is offering replacement swabs for customers who have a recalled one.
Flowflex
- Availability: Over the counter at most major pharmacies
- Ages: 2 and older
- Cost: $10
- Sensitivity: 93 percent (95% CI: 81% – 99%)
- Specificity: 100 percent (95% CI: 97% – 100%)
Authorized by the FDA in October, ACON Laboratories’ Flowflex is another rapid antigen home test. With one test per box, the nasal swab, lateral flow test gives results in about 15 minutes and can be used for those with and without symptoms. The Flowflex home test showed a higher sensitivity for detecting the Delta variant compared to other antigen rapid tests, according to performance tests published in The Lancet on November 24. CVS and Walgreens are selling the tests for $10.
Quidel QuickVue
- Availability: Online, most over the counter pharmacies
- Ages: 2 and older
- Cost: $24
- Sensitivity: 84.8 percent
- Specificity: 99.1 percent
Quidel’s QuickVue at-home rapid antigen test takes about 10 minutes and can be found at most pharmacies. We found it at CVS for $24. Quidel recommends that you use the test within six days of the first signs of symptoms or potential exposure. It comes with two tests; you should take the second test one to two days after you take the first.
How accurate are the at-home COVID-19 tests?
In general, PCR tests are more sensitive and specific than rapid antigen tests. Because Quest’s and Labcorp’s tests are taken at home and sent back to their labs for testing, each of those tests’ sensitivities and specificities are close to 100 percent. DxTerity’s test, which uses a saliva sample that’s sent to the company’s lab for testing, has a 97.2 percent sensitivity and a 92.5 percent specificity.
Ellume, maker of one of the handful of tests in which the samples and results are given at home, reported that its test identifies positive cases (sensitivity) 95 percent of the time and negative cases (specificity) 97 percent of the time. This was based on a study of 198 symptomatic and asymptomatic users and the results were compared against PCR testing.
Abbott pitted its BinaxNOW Self Test—another totally at-home COVID-19 test—against PCR tests in 460 symptomatic patients. The company found that if users were within seven days of symptom onset, BinaxNOW agreed with positive PCR results about 85 percent of the time and with negative PCR results about 98 percent of the time.
But when zoomed out to users within two weeks of symptoms, agreement with positive PCR results fell to 77 percent. Independent tests of BinaxNOW suggest the antigen test correctly identifies the virus 64 percent of the time for those with symptoms, and only 35 percent of the time in asymptomatic people. However, it did accurately identify negative results (in those that don’t have COVID-19 according to PCR) almost 100 percent of the time.
The last test we looked at, Cue, was evaluated in 292 symptomatic and asymptomatic individuals by a team of researchers at the Mayo Clinic, who recently published their results in the journal Diagnostic Microbiology and Infectious Disease. The Mayo Clinic team found that the Cue test had a positivity rate of between 91.7 and 95.7 percent and a specificity of 98.4 percent.
When to use an at-home COVID-19 test
Experts say that diagnostic testing—whether at home or at clinics and community sites—will continue to be critical in preventing the spread of future concerning variants and bringing an end to the pandemic.
Right now, there’s a lot to keep our eye on. 61 percent of the US population is fully vaccinated, while 27 percent have received boosters. But the COVID-19 death toll saw an uptick in the fall and early winter months. As of December 1, 2021, there are still about 118,000 new cases daily, and about 1,150 lives are lost each day to the disease.
“Now’s not the time to give up on testing,” Denny says. “We need to double down.”
Overall, experts say, an expanded array of options for identifying positive cases will help us curb their proliferation. “The more we can do simple, regular, at-home testing, the less we need it,” Aspinall says. “It’ll become a habit, as easy as brushing your teeth.”
As we continue to reopen businesses, socialize, travel, and reduce mask mandates, home tests can prevent infected people from spreading the coronavirus. They can also fill in gaps for those who may have less access to in-person testing.
And they could be deployed during local outbreaks or clusters at nursing homes, prisons, or other residential facilities to quickly determine who’s sick, says Prathit Kulkarni, an infectious disease specialist at Baylor College of Medicine.
So how should you approach at-home tests? If you’re unvaccinated and symptomatic, they’re a great way to confirm a COVID-19 infection without risking a trip out of the house.
If you have no symptoms, and just want to know whether you can safely attend a family dinner or soccer game, an at-home test remains an imperfect way of self-screening. Remember: If the test comes back negative, there’s still the chance the result is false and you could accidentally expose others by being within six feet of them without a mask on.
Back in March of 2021, the FDA authorized so-called “serial” antigen tests that can be taken within days of each other, increasing confidence in the test results. That’s the case for Abbott’s BinaxNOW self-screen, which comes in a pack of two tests to be taken 36 hours apart.
Otherwise, there is an even better way to prevent yourself from spreading COVID-19 at gatherings, Kulkarni says: Get vaccinated. Being fully vaccinated, and getting a booster if eligible, significantly reduces your risk of getting and spreading COVID-19.