Used in vaccine development and diagnostic assays to detect neutralizing antibodies against the Omicron variant of SARS-CoV-2. The Fc tag enhances detection sensitivity in immunoassays and enables easy purification and immobilization on Fc receptor-coated surfaces. Commonly applied in ELISA, lateral flow tests, and pseudovirus neutralization assays to evaluate immune response and vaccine efficacy. Also utilized in therapeutic antibody screening and structural studies of spike protein interactions with host cell receptors.