Validation of COVID-19 Diagnostic Assays

VALCOR samples were tested with the initial panel at UZ Leuven using the TaqPath COVID-19 assay as a comparator (11 (link), 12 (link)). The initial panel testing was performed, between 1 April 2020 and 15 January 2021. Nucleic acids were extracted using the MagMax Viral Pathogen II extraction kit (ThermoFisher Scientific) on the KingFisher High Throughput platform. The target genes of Taqpath COVID-19 are N gene, ORF1ab gene, and S gene. The results were reported as log copies/mL based on the quantification cycle (Cq, also called Ct) value of the N gene. Detection of two or more target genes was considered a positive result. Samples were reported negative when all viral gene targets were Cq > 37 and the MS2 internal control was Cq < 27.5. VL was estimated using a standard curve and semi-quantitatively reported (14 (link)). In case of discordance between the initial panel testing and the TaqPath COVID-19 assay, a third assay, either Abbott Alinity m system (IL, USA), Aptima SARS-CoV-2 assay (Hologic Panther system, MA, USA) (12 (link)), or Xpert Xpress SARS-CoV-2 assay (Cepheid GeneXpert system, CA, USA), was deployed as an adjudicator.