The peripheral blood amounts of several of these proteins measured at COVID-19 diagnosis, including serum lactate deshydrogenase,18 C-reactive protein and serum amyloid A,19 plasma tissue plasminogen activator and plasminogen activator inhibitor-1,20 serum angiopoietin-2,21 plasma pentraxin-3,16 and various cytokine profiles22, 23, 24 was associated with disease severity. Here, PTX3 is linked to COVID-19.