Figure 1.

The drizzle, the storm, and the hurricane: three different phenotypes of disease severity for COVID-19. The three main clinical phenotypes are represented. (a) Normal immunological response against viral infection. The clinical picture is typical of mild and self-limiting SARS-CoV2 infection. (b) The cytokine release syndrome (CRS) caused by the lysis of the immune cells may worse the clinical picture and lead to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). This immunological condition is typical of severe COVID-19 patients. (c) Critical patients present with a phenotype similar to a secondary Hemophagocytic Lymphohistyocitosis. The inflammasome is constantly triggered and produces large amounts of pro-inflammatory mediators which lead to life-threatening manifestations and multi organ failure (MOF). CRS: cytokine release syndrome; HLH: hemophagocyic lymphohistyocitosis; MAS: macrophage activation syndrome; MOF: multi organ failure; NLR: nod-like receptor; TLR: toll-like receptor. (A color version of this figure is available in the online journal.)