The FDA is warning that false negatives may occur with molecular tests used to detect SARS-CoV-2 if a mutation has occurred in the virus’s genome.
According to the FDA, the warning comes as public health officials warn about the new B.1.1.7 variant that appears to be more transmissible than the COVID-19 virus from 2020.
Three molecular tests that have received emergency use authorization have been analyzed by the FDA whose performance could be impacted by the new SARS-CoV-2 genetic variant:
- Mesa Biotech’s Accula SARS-CoV-2 test performance may be impacted when a SARS-CoV-2 virus patient sample has a genetic variant at position 28881 when tested. The FDA said the impact does not appear to be significant.
- Thermo Fisher Scientific’s TaqPath COVID-19 Combo Kit (also labeled as the TaqPath COVID-19 Combo Kit advanced) has significantly reduced sensitivity due to certain mutations in the SARS-CoV-2 virus, including one of the mutations int he recently identified B.1.1.7 variant. The FDA said that since the test can detect multiple genetic targets, the sensitivity should not be impacted.
- Applied DNA Sciences’s Linea COVID-19 Assay Kit has significantly reduced sensitivity in one of the two targets due to certain mutations, including the recently identified mutations B.1.1.7 variant. The overall test sensitivity should not be affected since it is designed to detect multiple genetic targets, according to the FDA.
The FDA said in a letter to healthcare workers it is currently working with companies whose authorized tests may be impacted to update labeling to reflect potential changes in the performance of the tests and will continue to keep healthcare providers updated.
The FDA also provided recommendations to address possible false negative results for clinical laboratory staff and healthcare providers who use the molecular tests:
- Be aware that genetic variants of SARS-CoV-2 arise regularly as false negative test results can occur.
- Be aware that tests that use multiple genetic targets for final results are less likely to be impacted by increased genetic variants of the virus.
- Consider negative results in combination with clinical observations, patient history and epidemiological information.
- Consider repeat testing with a different test, and with different genetic targets, if COVID-19 is still suspected after receiving a negative test.
The FDA will continue to monitor for new viral mutations and their impact on authorized SARS-CoV-2 molecular tests. It also said it will continue to monitor the emerging B.1.1.7 variant and evaluate authorized molecular test performances.