Figure 4 -. Promising therapeutic targets. (A) The clinical symptoms of COVID-19 appear after the first week of infection. In this first week, MASP-2 recognizes the N-SARS-CoV-2 protein and MBL recognizes S-SARS-CoV-2, leading to lectin pathway (LP) activation. Deficiency of C1-INH, proposed as a direct consequence of SARS-CoV-2 infection, leads to loss of physiological control of LP and coagulation, causing hyperinflammation and overcoagulation. During the second week, the symptoms start with activation of the classical pathway (CP) through the production of IgG and IgM antibodies, amplified by the alternative pathway (AP). At this stage of the disease, uncontrolled complement activation of all three pathways contribute to worsen the prognosis of COVID-19. (B) Drugs that inhibit the LP of complement can be considered as promising therapeutic agents against COVID-19. Those that inhibit MASP-1 and/or MASP-2 (Narsoplimab, C1-INH and antithrombin in the presence of low-molecular weight heparin - LMWH) are predicted to block both LP and coagulation, redirecting the clinical course of COVID-19 towards a better prognosis. This may also occur by reducing excessive antibody production, due to lower viral opsonization, phagocytosis and antigen presentation to B lymphocytes. AP - alternative pathway of complement; DIC - disseminated intravascular coagulation; C1-INH - C1 inhibitor; CP - classical pathway of complement; Ig - immunoglobulins; IL - interleukin; LP - lectin pathway of complement; MAC - membrane attack complex; MASP - mannose-binding lectin associated serine protease; NPC - new coronavirus pneumonia. Traced lines - weakened or blocked activation/ production. Solid lines - activation or blockage. Down-pointing arrows - lower production.