IFNG and COVID-19: In our cohort, the COVID-19 Cellular Immunity Test was based on the IFN-γ release assay (IGRA) using the recombinant SARS-CoV-2 S protein as a stimulus in whole blood, and we have shown that IFN-γ-SARS-CoV-2 S protein-specific levels were significantly higher in the COVID-19 group compared to the unexposed healthy group.