The genetic mutations in new strains of the coronavirus could affect the results of some COVID-19 tests, according to a warning from the Food and Drug Administration (FDA). Because the mutations affect the genetic component of the virus that these tests seek, the tests could end up with a false negative result, meaning that the negative results are only that disease is present.
The FDA recently discovered that three specific COVID-19 tests could produce a false negative result if the sample contains B.1.1.7 of the virus, which prompted a London lockout in December. It has since spread to other countries, including the U.S. The risk for negative negativity in this situation is low, according to the letter. But the FDA is raising the issue for healthcare workers and laboratory workers.
These three tests – the Accula SARS-Cov-2 Test, the TaqPath COVID-19 Combo Kit, and the COVID-19 Linea Assay Kit – all work by detecting specific parts of the genetic material of the coronavirus. Tests like this, which rely on polymerase chain reaction (PCR) technology to elevate small amounts of viral genetic material to visible levels, are thought to be the gold standard.
Both the TaqPath test and the Linea test are designed to detect a portion of the virus’ genetic material that affects its spike protein, which also occurs as one of the mutations present in the variant B.1.1.7. But that’s not the only target these tests are looking for, so the FDA says “the overall sensitivity of the test should not be affected. ”Even if the test does not detect one target area of the virus it is detecting due to a mutation in that region, the test should still pick up the virus with the other test target (s).
And when it comes to the Accula SARS-Cov-2 Test, its results could be affected if the strain has a different genetic mutation, one that has been found in some mutations, but not not present in B.1.1.7.
Overall, the FDA “believes that the risk of these mutations affecting clinical sensitivity is low,” meaning that, in practice, these trials are unlikely to be as sensitive in detects cases of COVID-19. But the FDA generally advises providers to be aware of the continuing potential for false negatives as new genetic changes arise.
That’s why it’s important for providers to take other factors into account when making a diagnosis, including the patient’s symptoms and epidemiological data for their location. (For example, if someone has COVID-19 symptoms and lives in an area where the virus spreads rapidly, it is likely that a negative test result is worth re-evaluating.) And if COVID-19 is still suspected after a negative test result, the FDA recommends re-testing the patient with a different test, with different genetic targets.
Finally, it’s important to keep in mind, though, that the B.1.1.7 variant that has been catching headaches is associated with a greater risk for transmission, according to the Centers for Control and Prevention Disease (CDC), does not appear to be the cause. illness worse or more fatal. And, importantly, experts say that the COVID-19 vaccines we currently have are likely to be just as effective against these strains.
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