At the start of the COVID-19 pandemic, there was no way to know if you had the virus unless you could get a PCR test from a medical professional. Tests were scarce, and long delays in getting results made finding out your COVID-19 status difficult. As a result, the launch of home COVID-19 tests, also known as antigen tests, has been welcomed by many.
At the time these tests were introduced, several reports indicated their accuracy 80%, with individual brands often reporting higher numbers. But a recent study by researchers at the California Institute of Technology now indicates that home COVID-19 tests are only 44% accurate.
The small study published in June in the journal Spectrum of microbiologyThe researchers analyzed data from 17 people with COVID-19, tracking when the virus appeared in the throat, saliva and nose, along with how well COVID-19 tests were able to detect the virus.
In general, the researchers discovered that the virus appeared in the throat or saliva several days before it appeared in the nose, which is the area that is swabbed in most home Covid-19 tests. The vast majority of study participants (88%) also had high levels of the virus in their bodies for at least a day before they got their positive antigen test result.
The data showed that home COVID-19 tests are not nearly as reliable as many people assume, with the researchers noting in the study that the tests have “low observed clinical sensitivity”.
The results of the study raise some concern, especially with the emergence of new variants of the Eris and Pirola coronaviruses. What does this mean for home COVID-19 tests, and will they be accurate even against the latest strains of the virus? Here’s what you need to know.
How accurate are COVID-19 tests?
The answer is not simple. In general, PCR tests (i.e., tests you take in a doctor’s office or clinic) are the gold standard in detecting coronavirus (COVID-19). Dr. Thomas RussoThe chair of the division of infectious diseases at the University at Buffalo in New York tells Yahoo Life. Home tests are a little different.
“When it comes to home tests, it’s really important to understand the question you’re asking the test to answer.” Dr. Amesh Adalja, a scientist at the Johns Hopkins Center for Health Security, tells Yahoo Live. “The test is not something that can pick up any amount of virus, but higher levels of virus – and it should be interpreted in that context.”
There are many factors that can affect the accuracy of test results; Russo says these include whether you have symptoms of coronavirus (COVID-19) and how often you tested positive for the disease.
If you have symptoms of coronavirus (COVID-19) and your home test is positive, “the likelihood of you getting COVID-19 is very high,” Russo says. “But if you have symptoms and the test is negative, you shouldn’t say, ‘Yes, yes!’ “I don’t have Covid,” he says. This is especially true if you’ve recently been exposed to someone with the virus, including a family member, Russo says.
Test results can also be less accurate if you don’t have symptoms — if you’re already infected but get a negative test result, it may simply be because virus levels aren’t high enough in your nose yet. “It was discovered,” Russo says.
The results of the study raise questions about a Penetration testing that circulated on social media in 2021, which recommended swabbing your nose and throat to get more accurate test results. The Food and Drug Administration later said X (formerly Twitter) that people should avoid the practice, noting that “those swabs are for your nose, not your throat.”
But the lead author of the study about home tests, Alexander Viloria WinnettThe latest findings raise questions about whether you’d get more accurate results if you could swab your nose, says a member of the UCLA-Caltech Medical Scientists Training Program. And throat. “Our data suggests that a combination nose and throat swab would produce better outcomes,” he told Yahoo Life. “But the tests need to validate that. We need to make sure the tests can handle it.”
While home COVID-19 tests have not been approved by the US Food and Drug Administration (FDA) for use in the throat, Adalja suggests going that route. “There has always been some disagreement between throat samples and nose samples,” he says. “Often, I recommend that individuals take a swab of their throat, even if that is not the intended use of the test, to increase sensitivity.”
Can home tests detect these new variants?
Eris (EG.5) and Pirola (BA.2.86) are fairly new. She had only recently become an Iris The most common variant of COVID-19 In the United States, there is only A few cases of BA.2.86 discovered worldwide.
However, there isn’t a lot of solid data yet on how well home COVID-19 tests pick up on these strains. However, experts say New variables must be discovered by home tests.
Russo explains that both iris and pyrrola have multiple mutations in the spike protein, which is what the virus uses to attach itself to your cells. But home tests don’t rely on spike protein — they depend on protein Nucleocapsid antigenHe says. “There are some changes in the nuclear capsid protein (in the newer strains), but the home test is expected to still be able to pick up these new strains.”
However, says Russo, “one cannot rule out the possibility that the sensitivity of the tests will decrease, should changes occur.”
Overall, Russo recommends that people keep this in mind: “A positive test is helpful, but a negative test doesn’t mean you don’t have Covid, especially if you have symptoms.” If you have symptoms of the virus and test negative, he suggests retesting yourself in a day or two or calling your doctor for a PCR test.