However, recently, studies on a novel cell type MDSCs, although not conclusive, are emerging to elucidate that, far from being clear, implicate TGF-β in COVID-19 MDSCs as suppressing CD4+ CD25+ Foxp3+ cells and evoking CD4+ CD25−Foxp3+ expansion, affecting TREGS, the autoreactivity of T cells, and suppressing IFN-γ [187,386]. This evidence concerns the gene CD4 and COVID-19.