Diagnostic Efficiency of Three Fully Automated Serology Assays and Their Correlation with a Novel Surrogate Virus Neutralization Test in Symptomatic and Asymptomatic SARS-COV-2 Individuals

To support the deployment of serology assays for population screening during the COVID-19 pandemic, we compared the performance of three fully automated SARS-CoV-2 IgG assays: Mindray CL-900i(R) (target: spike [S] and nucleocapsid [N]), BioMerieux VIDAS(R)3 (target: receptor-binding domain [RBD]) and Diasorin LIAISON(R)XL (target: S1 and S2 subunits). A total of 111 SARS-CoV-2 RT-PCR- positive samples collected at >= 21 days post symptom onset, and 127 pre-pandemic control samples were included. Diagnostic performance was assessed in correlation to RT-PCR and a surrogate virus-neutralizing test (sVNT). Moreover, cross-reactivity with other viral antibodies was investigated. Compared to RT-PCR, LIAISON(R)XL showed the highest overall specificity (100%), followed by VIDAS(R)3 (98.4%) and CL-900i(R) (95.3%). The highest sensitivity was demonstrated by CL-900i(R) (90.1%), followed by VIDAS(R)3 (88.3%) and LIAISON(R)XL (85.6%). The sensitivity of all assays was higher in symptomatic patients (91.1-98.2%) compared to asymptomatic patients (78.4-80.4%). In correlation to sVNT, all assays showed excellent sensitivities (92.2-96.1%). In addition, VIDAS(R)3 demonstrated the best correlation (r = 0.75) with the sVNT. The present study provides insights on the performance of three fully automated assays, which could help diagnostic laboratories in the choice of a particular assay according to the intended use.

Automated summary

This study compared the performance of three fully automated SARS-CoV-2 IgG assays and found that LIAISON(R)XL had the highest specificity while CL-900i(R) had the highest sensitivity. All assays had higher sensitivity in symptomatic patients, showed good correlation with sVNT, with VIDAS(R)3 demonstrating the best correlation.