CHARLOTTESVILLE, Va. (WVIR) – At home COVID-19 tests may be convenient, but some doctors are raising concerns about how well they detect certain variants. You’re going to have to be extra careful next time you go shopping for a home test.
Doctors with UVA Health say there’s early data that shows some home tests may not capture all of the omicron subvariants the same.
“There is a little bit of variation and it’s essentially unknown which test does well with which variant and so this may be a bit of a moving target, unfortunately,” Dr. Amy Mathers with UVA Health said.
Mathers specializes in infectious disease at the UVA Medical Center. She says the good news is they know one home test does work with BA.2.
“Some of the new tests like the BinaxNOW, went ahead and did a sub study and showed that nope, they can detect the newer variant,” Mathers said. “But that’s not true of all home tests.”
This new information isn’t to say other brand won’t work at all. Mathers says you’re just more likely to get a false negative with some of the tests.
“All the tests have proprietary chemistry that they use and so slightly different binding and slightly different algorithms for the way that they are able to pick up and test positive,” Mathers said.
Mathers says this makes different variants interact with that chemistry slightly differently, so sensitivity changes with various variants.
Doctor Costi Sifri with UVA Health says this data is new, though he has seen most of the tests have multiple, different targets for the virus spike protein that is important for detection.
“It is important to note that it does remain a possibility that we could see a variant that ends up not being detected by one test or another,” Sifri said. “That is something that is continually being evaluated as new variants arise.”
Mathers says if you are symptomatic and have a negative home test, you should wait a day, test using a different brand. She also recommends getting a PCR test, which she says will be the most accurate.
“What we do know is there’s actually a delay, even sometimes after you get symptoms by a day, for your antigen test to test positive,” Mathers said. “The PCR test is more sensitive early on.”
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