Coronavirus Variants May Lead To False Negative Results

Genetic variants of the novel coronavirus

Genetic variants of the novel coronavirus, including the one found in UK, could impact the performance of some molecular COVID-19 tests and lead to false negative results, the U.S. Food and Drug Administration (FDA) said on Friday.

U.S. drugs regulator

The U.S. drugs regulator said on Friday genetic variants of COVID-19, including the one found in the UK, could lead to false negative results from some molecular COVID-19 tests, but the risk of the mutations affecting overall testing accuracy is low.

U.S. Food and Drug Administration (FDA)

The U.S. Food and Drug Administration (FDA) said it has alerted lab staff and healthcare providers to the possible false negative results and has asked them to consider such results in combination with clinical observations, and use a different test if COVID-19 is still suspected.

Variants

Variant B.1.1.7 and other genetic variants may impact the performance of certain diagnostic tests, and the agency emphasized false-negative results can occur if a mutation occurs in a part of the virus’s genome being assessed by the test. Therefore, tests that rely on multiple regions of the genome may be less impacted than those that only rely on a single region, the FDA said.

B.1.1.7

Because the B.1.1.7 variant is thought to be more transmissible, “early identification of this variant may help reduce spread of infection,” the agency said. Still, it characterized the impact to overall testing accuracy as “low” and cited no episodes of actual false-negative results.

Agency Alerted Clinical Laboratory

The agency has alerted clinical laboratory staff and health care providers to the possible false negative results from any molecular test, and has asked them to consider such results in combination with clinical observations, and repeat testing with a different test if COVID-19 is still suspected.

Three Specific Tests

The agency highlighted three specific tests for which the variant may potentially impact test performance, including reduced sensitivity to certain mutations:

  • Accula SARS-CoV-2 Test (Mesa Biotech)
  • Taq Path COVID-19 Combo Kit (Thermo Fisher Scientific)
  • Linea COVID-19 Assay Kit (Applied DNA Sciences)

In fact, there may be a benefit with those two tests: “Importantly, the detection pattern that appears with the Taq Path 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,” the agency said.

The FDA said on Friday its analysis found the performance of three tests, that have received emergency use authorization, to be impacted by genetic variants of the coronavirus, but noted that the impact does not appear to be significant.

Contagious Variant

The more contagious variant of COVID-19 that has swept through the United Kingdom has been reported in at least five U.S. states, National Institutes of Health Director Francis Collins said this week.

Scientists have said newly developed vaccines should be equally effective against the new variant.

The performance of Mesa Biotech’s Accula test can also be impacted by the genetic variants, the health regulator added.

Thermo Fisher Scientific

Thermo Fisher Scientific Inc’s Taq Path COVID-19 combo kit and Applied DNA Sciences’ Linea COVID-19 assay kit were found to have significantly reduced sensitivity due to certain mutations, including the B.1.1.7 variant or the so-called UK variant, according to the agency.

Detection Patterns

The detection patterns of both tests may help with early identification of new variants in patients and since both the tests are designed to detect multiple genetic targets, the overall test sensitivity should not be impacted, the FDA said.

Mesa said its test would tolerate the genetic variation presented by the new strain and that it should not have an impact on clinical performance of the test.

Britain

Britain said in December rapid lateral flow tests being deployed in the country’s mass-testing program can identify the variant, while Roche said its molecular test for COVID-19 was unlikely to be affected by the mutant strain of the virus.

FDA Commissioner Stephen Hahn, MD

“At this time, we believe the data suggests that the currently authorized COVID-19 vaccines may still be effective against this strain,” said FDA Commissioner Stephen Hahn, MD, in a separate statement.