IFNG and COVID-19: Moreover, the conjugation of the receptor-binding domain (RBD) of the viral spike protein derived from the SARS-CoV-2 virus, along with α-GalCer, promoted an increase in SARS-CoV-2-specific IFN-γ+, TNF-α+, and IFN-γ+/TNF-α+ CD4+ T cells in comparison to the groups that were immunized with a mix of the RBD protein and α-GalCer [151], generating a novel candidate for a COVID-19 vaccine based on the immunomodulatory properties of iNKT cells.