Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria.
Department of Internal Medicine II, Infectious Diseases, Pneumology, Rheumatology, Medical University of Innsbruck, Innsbruck, Austria.
Clin Chem Lab Med. 2021 Apr 9;59(8):1453-1462. doi: 10.1515/cclm-2021-0214. Print 2021 Jul 27.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections cause coronavirus disease 2019 (COVID-19) and induce a specific antibody response. Serological assays detecting IgG against the receptor binding domain (RBD) of the spike (S) protein are useful to monitor the immune response after infection or vaccination. The objective of our study was to evaluate the clinical performance of the Siemens SARS-CoV-2 IgG (sCOVG) assay.
Sensitivity and specificity of the Siemens sCOVG test were evaluated on 178 patients with SARS-CoV-2-infection and 160 pre-pandemic samples in comparison with its predecessor test COV2G. Furthermore, correlation with virus neutralization titers was investigated on 134 samples of convalescent COVID-19 patients.
Specificity of the sCOVG test was 99.4% and sensitivity was 90.5% (COV2G assay 78.7%; p<0.0001). S1-RBD antibody levels showed a good correlation with virus neutralization titers (r=0.843; p<0.0001) and an overall qualitative agreement of 98.5%. Finally, median S1-RBD IgG levels increase with age and were significantly higher in hospitalized COVID-19 patients (median levels general ward: 25.7 U/mL; intensive care: 59.5 U/mL) than in outpatients (3.8 U/mL; p<0.0001).
Performance characteristics of the sCOVG assay have been improved compared to the predecessor test COV2G. Quantitative SARS-CoV-2 S1-RBD IgG levels could be used as a surrogate for virus neutralization capacity. Further harmonization of antibody quantification might assist to monitor the humoral immune response after COVID-19 disease or vaccination.
严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染可导致 2019 年冠状病毒病（COVID-19），并诱导特异性抗体反应。检测针对刺突（S）蛋白受体结合域（RBD）的 IgG 的血清学检测对于监测感染或接种疫苗后的免疫反应非常有用。本研究的目的是评估西门子 SARS-CoV-2 IgG（sCOVG）检测的临床性能。
在 178 例 SARS-CoV-2 感染患者和 160 例大流行前样本中评估了西门子 sCOVG 试验的灵敏度和特异性，并与前身 COV2G 试验进行了比较。此外，还在 134 例恢复期 COVID-19 患者的样本中研究了与病毒中和滴度的相关性。
sCOVG 试验的特异性为 99.4%，灵敏度为 90.5%（COV2G 试验为 78.7%；p<0.0001）。S1-RBD 抗体水平与病毒中和滴度呈良好相关性（r=0.843；p<0.0001），总体定性一致性为 98.5%。最后，中位 S1-RBD IgG 水平随年龄增加而升高，住院 COVID-19 患者（普通病房中位数：25.7 U/mL；重症监护室中位数：59.5 U/mL）明显高于门诊患者（3.8 U/mL；p<0.0001）。
与前身 COV2G 试验相比，sCOVG 试验的性能特征得到了提高。定量 SARS-CoV-2 S1-RBD IgG 水平可用作病毒中和能力的替代指标。进一步协调抗体定量可能有助于监测 COVID-19 疾病或接种疫苗后的体液免疫反应。
