Objective: We assessed the clinical performance of novel Roche Elecsys SARS-CoV-2 Antigen fully automated electrochemiluminescence immunoassay (ECLIA).
Design and Methods: We tested 160 subjects, 110 (68.8%) with positive molecular test for SARS-CoV-2 infection in nasopharyngeal samples with Altona Diagnostics RealStar SARS-CoV-2 RT-PCR Kit and Roche Elecsys SARS-CoV-2 Antigen. The local imprecision was validated by analyzing three nasopharyngeal samples with different antigen concentration (1.84, 9.51 and 423.30 TCID50/mL) for 20 consecutive times (intra-assay imprecision) or for 10 consecutive working days (inter-assay imprecision).
Results: The local intra- and inter-assay imprecision of Elecsys SARS-CoV-2 Antigen ECLIA was found to be comprised between 2.0-2.0% and 5.8-7.6%, yielding to a total imprecision of 6.2-7.8%. Highly significant correlation was found between Elecsys SARS-CoV-2 Antigen ECLIA and cycle threshold (Ct) values of SARS-CoV-2 S and E genes (both r=-0.91; p<0.001). The area under the curve (AUC), sensitivity and specificity of Elecsys SARS-CoV-2 Antigen ECLIA were 0.83, 0.43 and 1.00 in all samples, 0.99, 0.87 and 0.99 in those with both Ct values <30, as well as 1.00, 1.00 and 0.89 in samples with both Ct values <25.
Conclusion: Roche Elecsys SARS-CoV-2 Antigen ECLIA may be a surrogate of molecular testing for identification of super-spreaders.