CSB-EAP33245 is a solid phase sandwich Enzyme Linked-Immuno-Sorbent Assay (Sandwich ELISA). An antibody specific for SARS-CoV-2 Spike RBD has been pre-coated onto the microwells. The SARS-CoV-2 Spike RBD protein in samples is captured by the coated antibody after incubation. Following extensive washing, another antibody HRP conjugated specific for SARS-CoV-2 Spike RBD is added to detect the captured SARS-CoV-2 Spike RBD protein. Followed by Tetramethyl-benzidine (TMB) reagent. Solution containing sulfuric acid is used to stop color development and the color intensity which is proportional to the quantity of bound protein is measurable at 450nm.