Figure 2.

Clinical stages of COVID-19 (adapted with permission from Siddiqu and Mehra¹²⁵). During the first days from disease onset, patients typically present a first phase with symptoms resembling an upper respiratory tract viral infection, mostly characterized by fever and coughing. Over days 8–12 there is a transition to an inflammatory phase during which pulmonary symptoms such as shortness of breath might appear. In those patients progressing to the hyperinflammatory phase with relevant lung involvement, the risk of ARDS is notable. In addition, during this late phase, patients are at higher risk of suffering thrombotic and embolic events due to a procoagulant state. ARDS, acute respiratory distress syndrome; CRP, C-reactive protein; IL-1, interleukin 1; IL-6, interleukin 6; LDH, lactate dehydrogenase; NT-pro-BNP, natriuretic pro-brain natriuretic peptide; SIRS, systemic inflammatory response syndrome.