Commercially available SARS-CoV-2 RT-qPCR diagnostic tests need obligatory internal validation

Area of Science:

• Virology
• Molecular Diagnostics
• Public Health

Background:

• The ongoing evolution of SARS-CoV-2, particularly Omicron descendants, necessitates continuous vigilance and reliable diagnostic methods.
• Healthcare systems face persistent challenges due to increased transmissibility of new variants, making accurate detection imperative.

Purpose of the Study:

• To evaluate and compare the analytical performance of three commercially available SARS-CoV-2 diagnostic assays.
• To determine the specificity and sensitivity (Limit of Detection - LOD) of Liferiver, Vitaassay, and TaqPath RT-PCR kits for SARS-CoV-2, including the Omicron variant.

Main Methods:

• Analytical sensitivity and specificity were assessed using synthetic nucleic acid standards and clinical samples.
• Limit of Detection (LOD) was determined for each assay.
• Ct values were analyzed at specific viral RNA concentrations and compared to manufacturer-declared cutoff values.

Main Results:

• All three assays demonstrated 100% specificity for SARS-CoV-2 RNA and the Omicron variant.
• The LOD was 10 viral RNA copies/reaction for Liferiver and TaqPath, and 100 viral RNA copies/reaction for Vitaassay.
• Mean Ct values obtained were significantly lower than manufacturer-declared cutoffs, suggesting potentially higher sensitivity upon internal validation.

Conclusions:

• The evaluated RT-PCR assays are highly specific for SARS-CoV-2 and its Omicron variant.
• Internal validation of LOD and cutoff Ct values is crucial for accurate performance assessment, potentially revealing superior sensitivity compared to manufacturer specifications.
• Consistent and reliable detection of emerging SARS-CoV-2 variants remains critical for public health surveillance and management.