Coronavirus Mutations: FDA Singles Out 4 Molecular Tests That Can Give False Readings

Source : Medtech Insight

The US Food and Drug Administration has published a page on its website to update stakeholders about how mutations in the SARS-CoV-2 virus cause lower sensitivity of some COVID-19 tests and potentially give false readings. The page is meant to be a repository of the agency’s thinking on the subject as more information becomes available; the regulators have already listed four tests that have raised concerns.

The key to fighting the coronavirus pandemic and reopening the American economy hinges on vaccine distribution and screening for COVID-19, public health officials say. However, as the virus continues to mutate, officials are keeping an eye on how those genetic and viral changes may thwart tests and – more broadly – public screening efforts.

The FDA on 30 March published a new webpage that aggregates information the agency has been publishing over the past few months to highlight concerns about mutations that could lead to lower test sensitivity and false results.

Regulators singled out four molecular tests that have been given emergency use authorization (EUA) that may be prone to giving false results due to emerging mutations. The tests listed include:

Mesa Biotech Inc.’s Accula SARS-CoV-2 Test;

Applied DNA Sciences Inc.’s Linea COVID-19 Assay Kit;

Thermo Fischer Scientific Inc.’s TaqPath COVID-19 Combo Kit; and

Cepheid's Xpert Xpress SARS-CoV-2, Xpert Xpress SARS-CoV-2 DoD, and Xpert Omni SARS-CoV-2 tests.

Overall the FDA notes the tests still work for the most part, but if there are signs the test may be less sensitive due to a mutation in the virus, the agency makes a number of recommendations. For the TaqPath and Linea tests, the agency’s recommendation includes redoing the test with the Illumina COVIDSeq test, if possible.

“Changes in the viral genome can result in changes to viral proteins and, therefore, can also impact the performance of an antigen or serology test.” – US FDA

“If local or state clinical laboratories have access to quick turnaround whole genome sequencing services, such as those using the EUA-authorized Illumina COVIDSeq Test, these labs should consider further characterizing the specimen with genetic sequencing when this pattern is identified,” the FDA said. “If such services are not readily available, local or state clinical laboratories should consider reaching out to the Centers for Disease Control and Prevention at [email protected] for additional information.”

On the new webpage the FDA also points to its recently published guidance, “Policy for Evaluating Impact of Viral Mutations on COVID-19 Tests,” which test developers can use to address concerns about the sensitivity and accuracy of their tests as mutations of the coronavirus pop up around the world. ()

The FDA lists a number of factors clinical lab staff and health care providers need to be aware of when assessing the accuracy of a molecular test that may be negatively affected by a mutation. The agency added they should be aware of potential false-negative results that may 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.

“Changes in the viral genome can result in changes to viral proteins and, therefore, can also impact the performance of an antigen or serology test,” the FDA added.

By Ferdous Al-Faruque