Application of SARS-CoV-2 serology to address public health priorities

Background: Antibodies against SARS-CoV-2 can be detected by various testing platforms, but a detailed understanding of assay performance is critical.
Methods: We developed and validated a simple enzyme-linked immunosorbent assay (ELISA) to detect IgG binding to the receptor-binding domain (RBD) of SARS-CoV-2, which was then applied for surveillance. ELISA results were compared to a set of complimentary serologic assays using a large panel of clinical research samples.
Results: The RBD ELISA exhibited robust performance in ROC curve analysis (AUC> 0.99; Se=89%, Sp=99.3%). Antibodies were detected in 23/353 (6.5%) healthcare workers, 6/9 RT-PCR-confirmed mild COVID-19 cases, and 0/30 non-COVID-19 cases from an ambulatory site. RBD ELISA showed a positive correlation with neutralizing activity (p = <0.0001, R2 = 0.26).
Conclusions: We applied a validated SARS-CoV-2-specific IgG ELISA in multiple contexts and performed orthogonal testing on samples. This study demonstrates the utility of a simple serologic assay for detecting prior SARS-CoV-2 infection, particularly as a tool for efficiently testing large numbers of samples as in population surveillance. Our work also highlights that precise understanding of SARS-CoV-2 infection and immunity at the individual level, particularly with wide availability of vaccination, may be improved by orthogonal testing and/or more complex assays such as multiplex bead assays.

Amy C. Sherman, Teresa Smith, Yerun Zhu, Kaitlin Taibl, Jessica Howard-Anderson, Taylor Landay, Nora Pisanic, Jennifer Kleinhenz, Trevor W. Simon, Daniel Espinoza, Skyler Hammond, Nadine Rouphael, Huifeng Shen, Jessica K. Fairley, Jaime A. Cardona-Ospina, Alfonso J. Rodriguez-Morales, Lakshmanane Premkumar, Jens Wrammert, Rick Tarleton, Scott Fridkin, Christopher D. Heaney, Erin M. Scherer and Matthew H. Collins. Frontiers in Public Health, Oct. 2021, doi: 10.3389/fpubh.2021.744535