Performance of A Point-of-care Fluorescence Immunoassay Test to measure anti Severe Acute Respiratory Syndrome Corona Virus 2 Spike, Receptor Binding Domain Antibody Level

Quantitative determination of anti-SARSCoV2-S-RBD is necessary for the evaluation of vaccination effectiveness. Surrogate viral neutralization test (SVNT) is approved for measuring anti-SARSCoV2-S-RBD, but a point-of-care platform is needed to simplify anti-SARS-CoV-2-S-RBD measurement. We aimed to evaluate the performance of a rapid fluorescent immunoassay-based kit, FastBio-RBD tm , compared to SVNT. During April–September 2021, we enrolled two groups of subjects; convalescent subject and subject without COVID-19 history. Subjects were tested for anti-SARS-CoV2-S-RBD antibody using FastBio-RBD tm and GenScript-cPASS tm SVNT. We measured the correlation coefficient and conducted ROC analysis to determine the best cut-off value of anti-SARSCoV2-S-RBD against SVNT percent inhibition levels of 30% and 60%. We included 109 subjects. Anti-SARS-CoV-2-S-RBD strongly correlated to SVNT %-inhibition with R value = 0,866 (p < 0,0001). ROC analysis showed that anti-SARS-CoV-2-S-RBD of 6,71 AU/mL had 95,7% sensitivity and 87,5% specificity to detect percentage inhibition of 30%. Anti-SARS-CoV-2-S-RBD of 59,76 AU/mL had a sensitivity of 88,1% and specificity of 97,0% to detect percentage inhibition of 60%. FastBio-RBD tm can determine the presence and level of anti-SARS-CoV-2-S-RBD with good sensitivity and specificity. It has the potential to be deployed in health facilities with limited resources.