Validation and performance of a multiplex serology assay to quantify antibody responses following SARS‐CoV‐2 infection or vaccination

• Published in: Clinical & translational immunology 2022, Vol.11 (4), p.e1385-n/a
• Main Authors: Wilkins, Deidre, Aksyuk, Anastasia A, Ruzin, Alexey, Tuffy, Kevin M, Green, Tina, Greway, Rebecca, Fikes, Brittany, Bonhomme, Cyrille J, Esser, Mark T, Kelly, Elizabeth J
• Format: Article
• Language: English
• Subjects: Antibodies; Antigens; Clinical trials; Coronaviruses; COVID-19 vaccines; COVID‐19; electrochemiluminescence; Epidemiology; Immunization; immunoassay; Influenza; Nucleocapsids; Original; Polymerase chain reaction; Proteins; SARS‐CoV‐2; Sensitivity analysis; Serology; Severe acute respiratory syndrome coronavirus 2; Vaccination; Viruses
• ISSN: 2050-0068; 2050-0068
• DOI: 10.1002/cti2.1385

Objectives Robust, quantitative serology assays are required to accurately measure antibody levels following vaccination and natural infection. We present validation of a quantitative, multiplex, SARS‐CoV‐2, electrochemiluminescent (ECL) serology assay; show correlation with two established SARS‐CoV‐2 immunoassays; and present calibration results for two SARS‐CoV‐2 reference standards. Methods Precision, dilutional linearity, ruggedness, analytical sensitivity and specificity were evaluated. Clinical sensitivity and specificity were assessed using serum from prepandemic and SARS‐CoV‐2 polymerase chain reaction (PCR)‐positive patient samples. Assay concordance to the established Roche Elecsys® Anti‐SARS‐CoV‐2 immunoassay and a live‐virus microneutralisation (MN) assay was evaluated. Results Standard curves demonstrated the assay can quantify SARS‐CoV‐2 antibody levels over a broad range. Assay precision (10.2−15.1% variability), dilutional linearity (≤ 1.16‐fold bias per 10‐fold increase in dilution), ruggedness (0.89−1.18 overall fold difference), relative accuracy (107−118%) and robust selectivity (102−104%) were demonstrated. Analytical sensitivity was 7, 13 and 7 arbitrary units mL−1 for SARS‐CoV‐2 spike (S), receptor‐binding domain (RBD) and nucleocapsid (N) antigens, respectively. For all antigens, analytical specificity was > 90% and clinical specificity was 99.0%. Clinical sensitivities for S, RBD and N antigens were 100%, 98.8% and 84.9%, respectively. Comparison with the Elecsys® immunoassay showed ≥ 87.7% agreement and linear correlation (Pearson r of 0.85, P