FDA

COVID-19 Genetic Variants May Cause False Negatives on Diagnostic Tests

On January 8, 2021, the US Food and Drug Administration (FDA) released a letter to clinical laboratory staff and health care providers that warned new genetic variants of the SARS-COV-2 virus may cause false negative results on molecular-based tests.

 

False negatives can occur when mutations develop in the part of the virus’ genome that the molecular test assesses. Molecular tests that analyze multiple targets on the virus are less susceptible to genetic variation. However, all laboratory tests possess the risk for a false positive. The FDA continues to monitor the genetic variants of COVID-19 that arise and how these variants affect all the molecular tests that have received an Emergency Use Authorization. To date, the FDA has identified 3 tests that may be affected by the new genetic variants:

 

  • Accula SARS-CoV-2 Test
    • Genetic variant at position 28881 (GGG to AAC) may be impacted.
    • Currently, the change does not appear to be significant.
  • TaqPath COVID-19 Combo Kit
    • One of the 3 targets has significantly reduced sensitivity to the B117 variant as reported by the FDA, the manufacturer (Thermo Fisher Scientific, Inc.), and by multiple clinical laboratories.
    • Overall sensitivity should not be affected, as the kit tests for multiple targets.
  • Linea COVID-19 Assay Kit
    • One of the 2 targets has reduced sensitivity to the B117 variant as reported by the FDA and the manufacturer (Applied DNA Sciences, Inc.).
    • Overall sensitivity should not be affected, as the kit tests for multiple targets.

 

The FDA recommends clinical laboratory staff and other health care providers stay up to date on the genetic variants of COVID-19. Laboratories should use tests that target multiple genetic locations when possible to decrease the risk of false negatives. Additionally, if a patient’s test result is negative but has symptoms of or has been exposed to COVID-19, repeat testing should be considered.

 

—Audrey Amos, PharmD

 

Reference:

Genetic variants of SARS-CoV-2 may lead to false negative results with molecular tests for detection of SARS-CoV-2 – letter to clinical laboratory staff and health care providers. News release. US Food and Drug Administration; January 8, 2021. Accessed January 11, 2021. https://www.fda.gov/medical-devices/letters-health-care-providers/genetic-variants-sars-cov-2-may-lead-false-negative-results-molecular-tests-detection-sars-cov-2