IFNG and COVID-19: Lastly, an increase in the polyfunctional profile of both spike-specific CD4 and CD8 T cells was observed in convalescent COVID-19 patients compared to those in the acute phase of infection, characterized by a substantial increase in IFN-γ, TNF-α and IL-2 co-expressing cells for spike-specific CD4 T cells and a significant reduction of IFN-γ monofunctional cells for spike-specific CD8 T cells (Fig. S2B and C).