(ABC4) – On Monday, February 7, the Utah Department of Health announced they would pause the use of rapid antigen COVID tests at state testing sites. According to a press release, the decision was made due to new data that brought into question the accuracy of a specific brand of rapid test — GenBody — that was widely distributed amongst Utah state testing sites.
In the past, the accuracy of rapid tests has been questioned, with anecdotal evidence discussing these suspicions abounding. And, now that the state has confirmed these claims — at least in relation to one brand of test — can we trust the results garnered by the four free COVID tests recently provided by the United States government?
The answer is a complex one, but in short, yes.
According to Dr. Emily Spivak, an infectious disease physician at University of Utah Health, rapid antigen tests are 60-80% accurate for symptomatic cases and about 50% accurate for asymptomatic cases. Though they are not as reliable as the PCR tests — which experts regard as the gold standard for COVID diagnoses — she says that they are used because experts regard them as better for widespread use from a public health standpoint.
“While PCR may be the most accurate in telling if a person has COVID, if it takes two or three days to give them their results, that actually may backfire from a public health standpoint, because maybe [people are] not isolating during that,” she explains.
The rapid antigen tests, on the other hand, provide the ability to catch most cases early on, so people can know for sure whether to isolate.
Dr. Leisha Nolen, Utah’s state epidemiologist, adds that the chances of a false positive are extremely low, even with a rapid test.
“Almost any test, in fact, even this GenBody test, when it says you’re positive, you’re positive,” she says.
It’s the false negatives experts are more concerned about, especially for the asymptomatic cases.
“We know these tests have never done as well in people who are asymptomatic,” Dr. Nolen says. “That’s probably because you just have a lower level virus in your body.”
So what is the best approach to COVID testing?
As a general rule of thumb, it’s best to start with a rapid test, Dr. Nolen and Dr. Spivak agree. If it’s positive, it’s safe to assume you’ve contracted COVID. If it’s negative, but you’re having symptoms, that’s a good time to double check by scheduling a PCR test or taking a second rapid test after waiting a few days, Dr. Spivak says.
For asymptomatic individuals who have been exposed, Dr. Nolen says it’s appropriate to get a PCR COVID test if you plan to engage in a high-risk activity, like visiting an elderly relative or flying on a plane.
Additionally, Dr. Spivak says, because the rapid antigen tests are less sensitive, it’s best to wait a day after experiencing symptoms to test.
“If your rapid is negative, realize that there can be false negative, specifically in the first one to two days, and specifically with this variant, Omicron,” she says.
And though the initial Omicron surge appears to be subsiding, and the testing shortage that came with it is also waning, Dr. Nolen encourages Utahns to save the tests for those at risk of a more serious COVID infection.
And, even if you aren’t in a high-risk category, and you think you might have COVID but can’t get a test, stay home anyway.
“We really are trying to encourage people, if you have symptoms, we don’t really care what the test says too much,” Dr. Nolen says. “We want to make sure you don’t spread whatever you have to the next person.”