In fact, patients with severe respiratory failure with COVID-19 seem to exhibit a unique pattern of immune dysfunction: macrophage activation syndrome (MAS); interleukin (IL)-6-mediated very low human leukocyte antigen D related (HLA-DR) expression, with severe depletion of CD4+ T cells, CD19+ T cells and NK cells; and sustained production of cytokines and hyperinflammation [18]. This evidence concerns the gene CD4 and macrophage activation syndrome.