Genetic variants of SARS-CoV-2, the virus the causes COVID-19, may lead to false negative results with molecular tests for the virus. So what is FDA doing about it?
Just when we thought we had turned to a more promising chapter in the COVID-19 story, FDA is now warning that emerging viral mutations of SARS-CoV-2 could impact results of authorized COVID-19 molecular tests.
False negative results can occur with any molecular test for the detection of SARS-CoV-2 if a mutation occurs in the part of the virus’ genome assessed by that test, FDA said. The virus can mutate over time, like all viruses, resulting in a genetic variation in the population of circulating viral strains, as seen with the emerging variant from the United Kingdom known as the B.1.1.7 variant. The recently identified B.1.1.7 variant has been associated with an increased risk of transmission, therefore early identification of this variant in patients may help reduce further spread of infection.
What is FDA doing to ensure authorized COVID-19 tests remain accurate?
The agency said it is working with test developers and conducting ongoing data analysis to evaluate all currently authorized molecular tests. The good news, however, is that FDA believes the risk that these mutations will impact the overall accuracy of COVID-19 tests on the market is low.
COVID-19 tests that rely on the detection of multiple regions of the genome may be less impacted by genetic variation in the SARS-CoV-2 genome than tests that rely on detection of only a single region, the agency noted. FDA is also reminding clinical laboratory staff and healthcare providers about the risk of false negative results with all laboratory tests, including molecular tests. Laboratories should expect some false results to occur even when very accurate COVID-19 tests are used.
So far the agency has identified three currently authorized COVID-19 tests that may be impacted by genetic variants of the virus, but the impact does not appear to be significant. Those tests are: MesaBiotech Accula, TaqPath COVID-19 Combo Kit, and Linea COVID-19 Assay Kit. Importantly, the detection pattern that appears with the TaqPath and Linea diagnostic tests when certain genetic variants are present may help with early identification of new variants in patients to reduce further spread of infection, FDA said.
This news reinforces the importance of basing quarantine and treatment decisions on more than just COVID-19 test results. Click here to learn which COVID-19 tests have previously been flagged by FDA for potential inaccurate results.
As of Friday, Jan. 8, 311 COVID-19 tests and sample collection devices are authorized by FDA under emergency use authorizations. These include 235 molecular tests and sample collection devices, 64 antibody tests, and 12 antigen tests. There are 32 molecular authorizations that can be used with home-collected samples. There is one molecular prescription at-home test, one antigen prescription at-home test, and one over-the-counter at-home antigen test.