In patients with SARS-CoV-2–associated ARDS and purpuric skin rash, deposits of terminal complement components C5b-9 (membrane attack complex), C4d, and mannose-binding lectin (MBL)-associated serine protease (MASP)2 were found in both pulmonary and dermal microvessels, suggesting systemic activation of the alternative and lectin-based complement pathways (56). Here, MBL2 is linked to acute respiratory distress syndrome.