Evaluation of Commercially Available High-Throughput SARS-CoV-2 Serologic Assays for Serosurveillance and Related Applications

Mars Stone; Eduard Grebe; Hasan Sulaeman; Clara Di Germanio; Honey Dave; Kathleen Kelly; Brad J. Biggerstaff; Bridgit O. Crews; Nam Tran; Keith R. Jerome; Thomas N. Denny; Boris Hogema; Mark Destree; Jeff erson M. Jones; Natalie Thornburg; Graham Simmons; Mel Krajden; Steve Kleinman; Larry J. Dumont; Michael P. Busch

Disclosures

Emerging Infectious Diseases. 2022;28(3):672-683. 

In This Article

Abstract and Introduction

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveys can estimate cumulative incidence for monitoring epidemics, requiring assessment of serologic assays to inform testing algorithm development and interpretation of results. We conducted a multilaboratory evaluation of 21 commercial high-throughput SARS-CoV-2 serologic assays using blinded panels of 1,000 highly characterized specimens. Assays demonstrated a range of sensitivities (96%–63%), specificities (99%–96%), and precision (intraclass correlation coefficient 0.55–0.99). Durability of antibody detection was dependent on antigen and immunoglobulin targets; antispike and total Ig assays demonstrated more stable longitudinal reactivity than antinucleocapsid and IgG assays. Assays with high sensitivity, specificity, and durable antibody detection are ideal for serosurveillance, but assays demonstrating waning reactivity are appropriate for other applications, including correlation with neutralizing activity and detection of anamnestic boosting by reinfections. Assay performance must be evaluated in context of intended use, particularly in the context of widespread vaccination and circulation of SARS-CoV-2 variants.

Introduction

Serosurveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is critical to monitor the course of the evolving pandemic and local outbreaks and can provide data on infection-fatality ratios, vaccine coverage, the effect of mitigation measures, and levels of population immunity. Serosurveillance should be conducted with representative population sampling using well-characterized serologic assays selected on the basis of their performance characteristics and optimized algorithms. Using assays and algorithms that detect mild or asymptomatic infections is critical for accurately estimating cumulative incidence, and case-to-infection and death-to-infection ratios.

More than 85 SARS-CoV-2 antibody assays had received US Food and Drug Administration Emergency Use Authorization as of August 19, 2021, ranging from point-of-care tests to fully automated high-throughput platforms.[1] These assays target different immunoglobulins (total or selective IgG, IgM, or IgA) against viral antigens (full-length spike protein [S1/S2], subunit 1 [S1], subunit 2 [S2] of spike, the receptor binding domain [RBD] of spike, or the nucleocapsid protein [NC]).[1] Limited head-to-head evaluation data are available for high-throughput SARS-CoV-2 serologic assays, and few large-scale studies have focused on performance for serosurveillance applications. Comprehensive characterization of assay performance must include sensitivity, specificity, and durability of antibody detection over time since infection.

To provide a comprehensive overview and direct comparison of assay characteristics and performance to inform assay selection and results interpretation for serosurveillance, we conducted a multilaboratory comparative assessment of 21 high-throughput, commercially available SARS-CoV-2 serologic assays by using blinded panels of 1,000 highly characterized specimens, including longitudinal and cross sectional coronavirus disease (COVID-19) convalescent plasma (CCP) and prepandemic control plasma specimens. We distributed panels to experienced testing laboratories that were deemed to be proficient by the manufacturers and selected assays to represent multiple formats and antigen targets. Data from this study can inform assay selection and development of testing algorithms to meet the optimal performance characteristics for primary screening and supplemental testing in US and global serosurveillance studies. The study also provides performance data relevant to other serologic testing contexts that will enable clinicians, public health organizations, laboratorians, and emergency response planners to develop optimal algorithms for infection detection and confirmation, including vaccine breakthrough and recurrent infections and correlations with neutralizing activity.

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