Clinical assessment of SNIBE Maglumi SARS-CoV-2 antigen fully-automated chemiluminescent immunoassay

• Published in: Clinical chemistry and laboratory medicine Vol. 61; no. 8; pp. 1506 - 1510
• Main Authors: Pighi, Laura, Henry, Brandon M., De Nitto, Simone, Gianfilippi, Gianluca, Salvagno, Gian Luca, Plebani, Mario, Lippi, Giuseppe
• Format: Journal Article
• Language: English
• Published: Germany De Gruyter 26.07.2023; Walter De Gruyter & Company
• Subjects: antigen; Antigens; Automation; Chemiluminescence; Coronaviruses; COVID-19; Diagnostic systems; Immunoassay; infection; N protein; Population studies; SARS-CoV-2; Sensitivity; Severe acute respiratory syndrome coronavirus 2; Viral diseases; COVID-19; SARS-CoV-2; infection; antigen; immunoassay
• ISSN: 1434-6621; 1437-4331; 1437-4331
• DOI: 10.1515/cclm-2023-0181

Given that SARS-CoV-2 antigen tests will represent a pillar for supporting or surrogating molecular testing in the endemic period, we report here the clinical performance of the new SNIBE Maglumi SARS-CoV-2 antigen fully-automated chemiluminescent immunoassay (MAG-CLIA SARS-CoV-2 Ag). The study population consisted of 181 subjects (mean age 61 ± 21 years; 92 females) undergoing coronavirus disease 2019 (COVID-19) testing at the local diagnostic facility, from December 2022 to February 2023. Routine diagnostic practice involved the collection of a double nostril nasopharyngeal swab, analyzed in duplicate with SARS-CoV-2 antigen (MAG-CLIA SARS-CoV-2 Ag) and molecular (Altona Diagnostics RealStar SARS-CoV-2 RT-PCR Kit) tests. A significant Spearman's correlation was found between MAG-CLIA SARS-CoV-2 Ag and mean Ct values of SARS-CoV-2 and genes (r=-0.95; p<0.001). In all nasopharyngeal samples, the area under the curve (AUC) of MAG-CLIA SARS-CoV-2 Ag was 0.86 (95% CI, 0.81-0.90), with 0.71 sensitivity and 1.00 specificity at 7 ng/L cut-off, increasing to 0.98 (95% CI, 0.96-1.00) AUC and 0.96 sensitivity (with 0.97 specificity) in high viral load samples. When SARS-CoV-2 N protein concentration was replaced with raw instrumental readings (i.e., relative light units [RLU]), the AUC in all samples increased to 0.94. A RLU value of 945 was associated with 88.4% accuracy, 0.85 sensitivity, 0.95 specificity, 0.77 negative predictive value (NPV) and 0.97 positive predictive value (PPV), respectively. We found satisfactory analytical performance of MAG-CLIA SARS-CoV-2 Ag, which could be used as surrogate of molecular testing for identifying high viral load samples. Broadening the reportable range of values may generate even better performance.