UK Variant Of Coronavirus May Be Harder To Diagnose With Many Current Tests: FDA

Source : Medtech Insight

The US Food and Drug Administration alerted clinical laboratories and health care providers that mutations in the SARS-CoV-2 virus, including the B.1.1.7 variant, may result in false negative readings  on molecular diagnostic tests for COVID-19 .

The B.1.1.7 variant was discovered first in the UK back in October and is far more contagious than previous variants of the virus. Since the pandemic began, the FDA has allowed a slew of emergency use authorizations for COVID-19 molecular diagnostic tests, and is reviewing data to ensure they are safe and effective. Agency analysis of three diagnostic tests, suggests that they could give people the false impression that they are not infected as the virus continues to mutate.

“We are working with authorized test developers and reviewing incoming data to ensure that health care providers and clinical staff can quickly and accurately diagnose patients infected with SARS-CoV-2, including those with emerging genetic variants.” – Stephen Hahn

In an 8 January letter to stakeholders, the FDA says it is continuing to monitor the potential impact of mutations on molecular diagnostic tests but says so far, the overall impact on the accuracy of the tests is low.

"While these efforts continue, we are working with authorized test developers and reviewing incoming data to ensure that health care providers and clinical staff can quickly and accurately diagnose patients infected with SARS-CoV-2, including those with emerging genetic variants,” said FDA commissioner Stephen Hahn. “At this time, we believe the data suggests that the currently authorized COVID-19 vaccines may still be effective against this strain. The FDA will continue to keep health care providers and the public informed of any new information as it becomes available." 

The agency notes that tests that rely on detecting multiple regions of a virus’ genome may be less susceptible to giving false negative results than tests that rely on identifying only one region of the virus.

As a result of the FDA’s review, the agency noted that MesaBiotech Accula, TaqPath COVID-19 Combo Kit, and Linea COVID-19 Assay Kit, which are all authorized under EUAs, may be affected by genetic variants of the virus -- though the agency says the impact does not seem to be significant.

While the TaqPath and Linea diagnostic tests are less successful at detecting new mutations, the FDA says their detection patterns could ultimately help detect new variants of the virus in patients sooner and thereby help control the spread of the disease.

The FDA says it is working with test developers to update their product labels to highlight the concern about genetic variants leading to false negative results.

For the time being, regulators are urging laboratories and providers to keep in mind false negatives may result from genetic variants, as well as that tests that look for multiple genetic targets are less likely to be impacted. They are also encouraging health care professionals to consider other factors such as clinical observations, patient history and epidemiological information to make a final diagnosis when a patient receives a negative result. Furthermore, when a patient has a negative reading, providers should consider using another molecular test with a different genetic target to increase the chances of detecting the virus.

“The FDA has reminded clinical laboratory staff and health care providers about the risk of false negative results with all laboratory tests, including molecular tests,” the FDA said. “Laboratories should expect some false results to occur even when very accurate SARS-CoV-2 tests are used.”

Concerns about false negative results have plagued the FDA’s efforts to get reliable tests to market almost from the start. The agency had to pull a slew of COVID-19 antibody tests off the shelves early in the pandemic. ()

Most recently, the agency issued a safety communication for Curative Health Services Inc.’s SARS-CoV-2 molecular diagnostic test stating that the tests could result in false negative results if usage instructions are not properly followed. ()

By Ferdous Al-Faruque