TNF and macrophage activation syndrome: Even though plasma concentrations of IL-6, IL-8, and tumor necrosis factor-α (TNF-α) in severe COVID-19 patients may be lower than subjects affected by septic shock and similar to levels found in other patients in a critical state (6), the inflamed phenotype correlates with poor COVID-19 prognosis and is generated by cytokine storm, a condition characterized by macrophage activation syndrome, lymphopenia and organ mononuclear cell infiltration (7).