November 29, 2021 – Thermo Fisher Scientific Inc. (Waltham, MA) today confirmed that its polymerase chain reaction (PCR) TaqPath COVID-19 Combo Kit, and TaqPath COVID-19 CE-IVD RT-PCR Kit, which test for the presence of SARS-CoV-2, are not impacted by the emerging B.1.1.529, or Omicron variant, enabling accurate test results.
The Omicron variant, which was designated a “variant of concern” by the World Health Organization (WHO), has more than 30 mutations in the spike protein alone. The WHO has reported that preliminary evidence suggests an increased risk of transmission compared to other variants of concern. The WHO and European Centers for Disease Control have both reported that using S-gene target failure (SGTF) of the PCR assays as a proxy for the variant helped to identify Omicron.
The TaqPath COVID-19 assays detect SARS-CoV-2 infections by identifying the presence of three gene targets from the orf1a/b, S, and N regions of the virus. By surveying across multiple genes, the test can report accurate results even in the case where one of the targets is impacted by a mutation.
While the S gene target in the test is impacted in the presence of Omicron variant mutations, the orf1a/b and N gene targets in the TaqPath COVID-19 tests have been determined to not be impacted by any of the mutations in the Omicron variant, based on assessment of sequences in the GISAID public database. As a result, the overall accuracy of the TaqPath COVID-19 assays is not impacted, the company says.
The Omicron variant has been found to include the 69-70del mutation of the S gene, first identified as a mutation in the Alpha variant. This mutation causes a dropout of the S-gene target in results from the TaqPath test, which could indicate to clinicians and researchers a possible Omicron variant infection. Confirmation must then be performed by sequencing the sample.
Specific genotyping assays to detect the Omicron variant are being developed for Thermo Fisher’s TaqMan Mutation Panel. The panel, which is currently used for research purposes, already has a menu of over 50 assays to assess confirmed COVID-19 cases for the presence of known variants and mutations.
The original TaqPath kit received emergency use authorization from the United States Food and Drug Administration (FDA) in March 2020, and the 2.0 version of the kit received EUA in August 2021. The TaqPath COVID-19 CE-IVD RT PCR Kit launched in March 2020 and the 2.0 version launched in June 2021.