Optimized cut-off for IgG improved the sensitivity to reach 100% (95%CI: 87.6-100) from 28 days since symptom onset. After 2 weeks since symptom onset, the sensitivities for IgM and IgG were 62.2% (95% CI: 52.3-71.2%) and 92.9%% (95% CI: 85.7-96.7%), respectively by using the cut-off provided by the manufacturer. This iFlash® SARS-CoV-2 assay showed excellent analytical performance. The specificity analysis was performed from 75 selected non-SARS-CoV-2 sera with a potential cross-reaction to the SARS-CoV-2 immunoassay. Sensitivity analysis was performed by using 178 sera collected from 154 RT-PCR confirmed COVID-19 patients. The precision, carry-over, linearity, limit of blank, detection and quantification were assessed.
The kinetics of the antibody response was also evaluated. This study aims at assessing the analytical and clinical performance of the iFlash® anti-SARS-CoV-2 chemiluminescence assay for the detection of both IgM and IgG antibodies. Electronic address: serological SARS-CoV-2 immunoassays have been developed recently but require external validation before widespread use. 7 Department of Pharmacy, Namur Research Institute for LIfes Sciences, University of Namur, Belgium Qualiblood sa, Namur, Belgium.6 Department of Pharmacy, Namur Research Institute for LIfes Sciences, University of Namur, Belgium.5 Department of Laboratory Medicine, Saint Nikolaus Hospital, Eupen, Belgium.4 Department of Pharmacy, Namur Research Institute for LIfes Sciences, University of Namur, Belgium Department of Laboratory Medicine, Iris Hospitals South, Brussels, Belgium Faculty of Medicine, Université libre de Bruxelles, Brussels, Belgium.3 Department of Laboratory Medicine, Clinique St-Luc Bouge, Namur, Belgium.