CD4 and COVID-19: In an ex-vivo study on peripheral-blood immune cells, we have also recently demonstrated that IL-10 treatment decreased the IFN-γ specific response to spike stimulation, decreased the release of numerous pro-inflammatory cytokines, chemokines and growth factors, reduced the frequency of IFN-γ producing CD4, CD8 and NK cells and cell activation (evaluated by HLA-DR expression), in both COVID-19 patients and NO COVID-19 vaccinated subjects (45).