EVALUATION OF THE STABILITY OF SARS-CoV-2 ANTIGEN IN CLINICAL SAMPLE AFTER MULTIPLE FREZEE-THAW CYCLES

Abstract

The standard panel for evaluation of diagnostic performance (sensitivity, specificity, etc.) is a set of samples containing different SARS-CoV-2 viral loads. Some studies have shown that antigen concentrations in clinical samples positive for SARS-CoV-2 after long-term storage at deep negative temperatures tend to be unstable [1]. We used a set of 10 positive SARS-CoV-2 for evaluating the effect of number of freeze/thaw cycles on the detection of SARS-CoV-2 by rapid antigen, testing on nasopharyngeal samples in virus transmission medium (VTM). This study showed that the nucleocapsid antigen SARS-CoV-2 remained detectable and over 5 FT cycles (without different significant and p >0.05. Moreover, our study results proved that retroproductive SARS-CoV-2 clinical samples can be used as the evaluation panel for quality control of in vitro diagnostic test kits detecting SARS-CoV-2 after 5 freeze/thaw cycles.