Diagnostic performance of an automated chemiluminescence immunoassay for SARS-CoV-2 IgG and IgM antibodies detection: A real life experience

Villalta, Danilo; Martelli, Paola; Moratto, Anna; Salgarolo, Valeria; Ligato, Elita; Conte, Mariaelisabetta; Giacomello, Roberto; Pellis, Tommaso; De Rosa, Rita; Venturini, Sergio; Crapis, Massimo

BACKGROUND: Recently many serological assays for detection of antibodies to SARS-COV-2 virus were introduced on the market. Aim of this study was to assess the diagnostic performance of an automated CLIA for quantitative detection of anti-SARS-CoV-2 IgM and IgG antibodies. METHODS: A total of 354 sera, 89 from consecutive patients diagnosed with COVID-19 (43 mild, 32 severe and 13 critical) and 265 from asymptomatic and negative on rRT-PCR testing healthcare workers, were evaluated for IgM and IgG anti-SARS-CoV-2 antibodies with MAGLUMI immunoassay. RESULTS: The overall sensitivity and specificity were 86.5% (95%CI: 77.6–92.8) and 98.5% (95%CI:96.2–99.6), respectively. PPV, PPN, LR+, LR- and OR were 95.1 (95%CI: 87.8–98.6), 95.6 (95%CI: 92.4–97.7), 57.3 (95%CI: 21.6–152.1), 7.3 (95%CI: 4.31–12.4) and 418.6 (95%CI: 131.2–1335.2), respectively. The levels of SARS-CoV-2 IgM and IgG antibodies were 1.22 ​± ​1.2 AU/mL and 15.86 ​± ​24.83 AU/mL, 2.86 ​± ​2.4 AU/mL and 69.3 ​± ​55.5 AU/mL, 2.47 ​± ​1.33 AU/mL and 83.9 ​± ​83.9 AU/mL in mild, severe and critical COVID-19 groups, respectively. A significant difference in antibody levels between mild and severe/critical subjects has been shown. CONCLUSIONS: The CLIA assay showed good diagnostic performance and a significant association between antibody levels and severity of the disease was found.