IFNG and COVID-19: The stimulation of PBMCs from COVID-19 patients with S protein peptides resulted in production of effector or Th1 cytokines (IFN-γ, TNF-α, and IL-2) and, to a lesser extent, Th2 (IL-5, IL-13, IL-9, and IL-10) and Th17 (IL-17A, IL-17F, and IL-22) cytokines [48].