COVID-19 Antibody Detection and Assay Performance Using Red Cell Agglutination

Area of Science:

• Immunology
• Virology
• Medical Diagnostics

Background:

• Serologic screening for SARS-CoV-2 antibodies is crucial for understanding infection dynamics and immunity.
• Existing antibody tests vary in performance and accessibility.
• Red blood cell-based assays offer a novel approach for antibody detection.

Purpose of the Study:

• To evaluate the analytical performance of a novel red blood cell-based assay (C-19 kodecytes) for detecting SARS-CoV-2 antibodies.
• To compare the C-19 kodecyte assay against established serologic and virus neutralization assays.
• To assess the scalability and practical application of the C-19 kodecyte assay in a clinical laboratory setting.

Main Methods:

• Red blood cells were labeled with SARS-CoV-2 spike protein peptides to create C-19 kodecytes.
• The C-19 kodecyte assay was used to test plasma from 140 COVID-19 convalescent donors and 275 healthy controls.
• Assay performance was compared with a virus neutralizing assay and two commercial chemiluminescent antibody tests (Total and IgG assays).

Main Results:

• The C-19 kodecyte assay demonstrated a sensitivity of 92.8% and a specificity of 96.3%.
• It showed almost perfect agreement with the Total assay (Cohen's kappa = 0.90).
• The assay is easily scalable and adaptable to existing blood typing laboratory platforms.

Conclusions:

• The C-19 kodecyte assay is a reliable and accurate method for SARS-CoV-2 antibody detection.
• Its high sensitivity and specificity meet FDA requirements for emergency use authorization.
• The assay's scalability and use of routine equipment make it suitable for population-wide screening and implementation in hospital blood banks worldwide.