Intravitreal injections of the C3 inhibitor Pegcetacoplan (APL-2) and the anti- Factor D antigen binding fragment (Lampalizumab) have shown effectiveness in macular degeneration (184, 185); the C3 inhibitor, APL-2, is also being evaluated for use in PNH and ALS; another C3 inhibitor, AMY-101, has proven effective for the management of gingivitis (186); factor D inhibitor, Danicoplan, has been trialed in PNH (187) and COVID-19, just to name a few. Here, C3 is linked to COVID-19.