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Kris

SARS-COV-2 Variants and Their Impact on Molecular Tests

As new variants of SARS-CoV-2 arise, they can impact diagnostic testing, potentially resulting in false negative results. To confidently make treatment decisions, achieve best-possible patient outcomes, and drive operational and clinical efficiency in a point-of-care setting, you need highly sensitive, rapid molecular tests capable of detecting all existing and emerging SARS-CoV-2 variants.

Which SARS-CoV-2 Tests Are Susceptible to False Negatives?

 

Molecular tests are straightforward to design for pathogen detection because they are largely based on an RNA sequence. However, viruses that rapidly evolve, such as SARS-CoV-2, can influence test sensitivity based on the sequence of the variant, the design of the test and the prevalence of the variant in the population.

Earlier this year, the FDA identified four EUA-authorized molecular tests that could be impacted by SARS-CoV-2 genetic variants, such as the B.1.1.7 variant that has been associated with an increased risk of transmission.1-2

It is important to be aware that genetic variants are expected to continue to emerge in SARS-CoV-2, which can threaten the sensitivity of virtually any molecular test. This is due to the possibility that one of the targets is driving the sensitivity, so that even if the others still match perfectly the sensitivity can be reduced based on a mutation in a single target. By choosing a test that uses multiple genetic targets, a test will be less likely to be impacted by increased prevalence of genetic variants.3

How To Know If SARS-CoV-2 Variants Impact Your Molecular Test?


Consider the patterns of detection
for your specific test. By choosing a test that uses multiple genetic targets, unfamiliar patterns may reveal the presence of new variants without impacting the final result of your test.

Stay up-to-date on emerging SARS-CoV-2 variants4, and their ability to evade detection by specific viral diagnostic tests.

Perform a repeat test. Per FDA recommendations5, consider negative results in combination with clinical observations, patient history and epidemiological information and repeat testing with a different test targeting different genetic regions if COVID-19 is still suspected.

How Do SARS-CoV-2 Molecular Tests Perform at the Point-of-Care?


All molecular tests used at the point-of-care are significantly faster than central-lab molecular tests 

Compared with central lab molecular tests, which may take up to several days, many point-of-care (POC) molecular test results are generated in up to 45 minutes6.

Point-of-care molecular tests integrated with nucleic acid extraction are more sensitive than those without this crucial sample preparation step

Not all POC molecular tests are created equal. There are some that incorporate nucleic acid extraction (e.g., Talis One) and many that do not, and this feature appears to influence the sensitivity of the test.7 Tests integrated with nucleic acid extraction can deliver significantly lower limits of detection (LoD)—with Talis One sensitivity approaching the range of lab-quality tests.7 Confirmatory testing for presumptive negatives may not be required.

Talis One provides rapid and accurate SARS-CoV-2 detection—quickly delivering central lab-quality results at the point of care

At Talis, we strive to use the best technology to bring the precision of lab-based molecular testing to the point-of-care. The Talis One Covid-19 Assay is designed to detect the ORF1ab and N gene (highly conserved regions) to remain sensitive in the presence of new variants and minimize the need for repeat testing. By integrating solid-phase extraction with innovative nucleic acid amplification technology, the Talis One COVID-19 Assay provides a sample-to-answer POC test where clear, actionable, highly sensitive results are generated in less than 30 minutes—helping healthcare providers enhance patient experience and patient outcomes.

Confidently determine who needs to quarantine and be treated to achieve better patient outcomes with the Talis One COVID-19 Test

Talis One COVID-19 Assay

Central lab-quality SARS-CoV-2 molecular testing for a variety of care settings—less than 30 minutes from sample to results.

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References

  1. SARS-CoV-2 Viral Mutations: Impact on COVID-19 Tests. U.S. Food and Drug Administration website. Updated June 3, 2021. Accessed June 25, 2021. https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/sars-cov-2-viral-mutations-impact-covid-19-tests
  2. Emergence of SARS-CoV-2 B.1.1.7 Lineage — United States. Centers for Disease Control and Prevention website. Updated January 22, 2021. Accessed June 25, 2021.https://www.cdc.gov/mmwr/volumes/70/wr/mm7003e2.htm
  3. SARS-CoV-2 E Gene Variant Alters Analytical Sensitivity Characteristics of Viral Detection Using a Commercial Reverse Transcription-PCR Assay https://journals.asm.org/doi/full/10.1128/JCM.00075-21 Accessed August 12, 2021
  4. Genetic Variants of SARS-CoV-2 May Lead to False Negative. U.S. Food and Drug Administration website. Updated March 30, 2021. Accessed June 25, 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
  5. Science Brief: Emerging SARS-CoV-2 Variants. Centers for Disease Control and Prevention website. Updated January 28, 2021. Accessed June 25, 2021. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/scientific-brief-emerging-variants.html
  6. Manufacturers’ instructions for use accessed August 12, 2021 at https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/in-vitro-diagnostics-euas-molecular-diagnostic-tests-sars-cov-2#individual-molecular
  7. Subsoontorn, P., Lohitnavy, M. & Kongkaew, C. The diagnostic accuracy of isothermal nucleic acid point-of-care tests for human coronaviruses: A systematic review and meta-analysis. Sci Rep 10, 22349 (2020). https://doi.org/10.1038/s41598-020-79237-7 Accessed August 12, 2021

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