IFNG and COVID-19: We also examined the production of inflammatory cytokines such as gamma interferon (IFN-γ), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) by T cells, NK cells, and NKT-like cells in CI, since a previous study demonstrated that significant numbers of T cells produce these cytokines during the acute phase of COVID-19 (21).