To date, the Food and Drug Administration (FDA) has authorized more than 45 antigen tests, including 17 at-home options. There are a few things you should know before you start playing Dr. Mom or Dr. Dad, though.
What Are At-Home COVID-19 Tests?
At-home, or antigen, tests are over-the-counter screenings used to detect an active Coronavirus infection on the spot. Some call for at-home sample collection and require a lab for interpretation, but for the most part, at-home antigen tests are quick, convenient, and affordable—and they can be completed entirely at home. Because it’s possible to get a false negative from an at-home antigen test, medical care providers tend to regard these tests as screening tools that help to detect COVID-19 and prevent it from spreading as opposed to absolute diagnostic tools. And most at-home tests require you to complete a second test 24 hours later to help further understand your results. Although antigen tests are not as sensitive as molecular, or polymerase chain reaction (PCR) tests, they are still useful. “They’re positive when someone is contagious, so to me, they’re helpful,” says Jennifer Lighter, MD, a pediatric infectious diseases specialist and hospital epidemiologist at NYU Langone.
How Do At-Home COVID-19 Tests Work?
At-home antigen tests use a nasal or oral swab to collect a mucus sample and rapidly detect fragments of COVID-19 proteins known as antigens, or substances that trigger an immune response.
When To Use an At-Home COVID-19 Test
“While at-home tests may be the quickest and most convenient option, they may not be the most appropriate for all situations,” according to the FDA, which recommends COVID-19 testing in the following scenarios:
If you have COVID-19 symptoms of COVID-19, even after getting vaccinatedIf you’ve been in close contact (within 6 feet for a total of 15 minutes or more) with someone with confirmed COVID-19, even if you’ve been vaccinatedIf you took part in activities that put you at higher risk for COVID-19 (i.e. situations where you can’t socially distance), such as travel, attending large gatherings, or being in crowded indoor settings.If you’ve been asked to get tested by your healthcare provider or state health department.
The best time to use an at-home antigen test, in particular, is when you need to quickly contain the spread of COVID-19 after potential exposure, according to a statement from the American Academy of Pediatrics (AAP). Say your daughter just came home from a birthday party when you find out a child in her recent dance class came down with COVID-19. A quick antigen test can tell you whether she has been infected so you can warn other birthday party guests ASAP—before they accidentally spread the virus further. That said, antigen tests generally have lower sensitivity and accuracy than PCR tests, according to the CDC, which recommends confirmation testing in certain cases—like gaining clearance to return to school. If you or your child is experiencing COVID-19 symptoms or you know you’ve been exposed to it, you should assume your positive antigen test is accurate, and get a PCR test to confirm a negative result.
How To Use At-Home COVID-19 Tests
Each FDA-approved at-home antigen test comes with their own instructions for use, but generally, you’d follow this process:Step 1: Insert a swap about 1/2 to 3/4 of an inch into one nostril. (This is important since you could get a false negative if you don’t insert it enough—but remember it’s not a nasopharynx swab, the extra-long one used to reach deep inside the nose during PCR tests, Dr. Lighter says). Swirl the swab around 3 to 5 times over 15 seconds to collect any and all fluids, then repeat on the other nostril using the same swab. Step 2: Insert the swab into the provided tube filled with liquid and swirl it for 30 seconds, rotate it, and squeeze the tube around the swab to release any liquid from the swab. Step 3: Dispense a portion of the liquid into a test sample well or strip and wait about 15 minutes before looking for one line (negative) or two lines (positive) on a test strip. One note you may find on instructions: “Test results should always be considered in the context of clinical observations and epidemiological data (such as local prevalence rates and current outbreak/epicenter locations) in making a final diagnosis and patient management decisions.” In other words, the tests don’t even trust themselves to be the last word on whether you have COVID-19—so context on potential exposures and PCR confirmation testing is key.
Are At-Home COVID-19 Tests Accurate When Used By Children?
In theory, yes—but their accuracy may be extra questionable due to the risk of human error, which any active toddler’s parent can thoroughly appreciate. “I have no concerns about accuracy based on age, but it can be more difficult to get a good sample if a child is squirming around,” Dr. Lighter says. As for children under two, at-home antigen tests haven’t been tested on them—but that’s not to say they wouldn’t detect the virus. “Although the noses of children under two may be smaller, and the swabs may be the wrong size for them, a positive test result is still reliable information,” Dr. Lighter says.
Limitations of At-Home COVID-19 Tests
While giving your child a COVID-19 test at home is convenient, it’s not perfect. If you’re truly concerned about a COVID-19 infection, your best bet is to get a PCR test to confirm any results.
Low Sensitivity
Because antigen tests are most accurate in detecting peaks in viral load that often correlate with the onset of symptoms, they’re not great at detecting COVID-19 before the onset of symptoms, Dr. Lighter says.
Inconsistent Reliability
“When you get a positive antigen test, you can be pretty darn sure that it is a rigorous result,” says William Schaffner, MD, a professor of infectious disease at the Vanderbilt University Medical Center in Nashville. “But when you get a negative test, it may not be a true negative.” If you or your child has no symptoms and no known exposures, you can likely trust a negative antigen test, but it’s still recommended to take a PCR test to confirm antigen test results, anyway. And remember: If you or your child are experiencing COVID-19 symptoms or have had a known, prolonged exposure to someone who is infected, and have received a negative antigen test, you can’t rule out infection and should get a PCR test to reaffirm your results. Positive results are more reliable: “If your child gets some mild symptoms—and you can expect a lot of snotty noses this winter now that kids are back in school with and without masks—you can be pretty sure that a positive antigen test is correct,” says Dr. Schaffner.
Human Error
At-home antigen tests leave room for error—unless you’re an actual doctor, you might not swab deep enough or collect enough of a sample to render an accurate read, particularly when your child is wriggling around.
Are At-Home COVID-19 Tests a Replacement for a PCR Test?
Experts agree the answer is no. “PCR tests look at part of the genome of the virus while antigen tests look at a piece of the protein of the virus,” explains Dr. Lighter. All a layperson needs to know is that the former is significantly more sensitive—and that the PCR test can remain positive weeks after a person ceases to be contagious. “It’s why only PCR tests should be used to diagnose,” she says. While there’s no question that at-home antigen tests are more convenient, PCR tests are the highest standard, Dr. Schaffner says. He explains that, unlike antigen tests, PCR tests enlarge or multiply the antigen so it can be detected. “Antigen tests aren’t as accurate as PCR tests not because the test malfunctions, but because antigen-tests aren’t as capable of picking up small amounts of virus,” he says. So while a positive antigen test is a pretty reliable sign that you’ve got COVID-19, particularly in conjunction with known exposure or COVID-19 symptoms, it’s smart to confirm a negative antigen test with a PCR test to rule out COVID-19 or get a PCR test in the first place.
Tips For Using an At-Home COVID-19 Test On a Child
When performing an at-home antigen test, it’s important to insert the test swab far enough into the nasal cavity—there may be a line on the swab indicating how deep to go—and make sure it spends ample time therein. After all, you could get a false negative if you don’t collect enough of a specimen to be detected by the test. If you’re trying to collect a nasal sample from a child who doesn’t love to sit still, it could be helpful to have a partner gently hold the child’s head in place while you swab their nose, or talk them through the process, Dr. Lighter suggests. And when swabbing little noses that may be shorter than the 1/2- to the 3/4-inch depth you’d typically need to reach based on most at-home antigen test instructions? Know that it’s OK to stay shallow on them. You can still collect a sufficient enough sample to perform the test—and should still follow up with a PCR test to confirm negative results when symptoms are present or in the case of known exposure.
