MPO and COVID-19: It attracts and activates cells among which monocytes, promoting inflammation, and thromboembolic events, and was recently found increased in serum from severe COVID-19 patients [19]; (ii) perinuclear anti-neutrophil cytoplasmic antibodies (pANCA), specifically addressed against neutrophil myeloperoxidase, previously found enhanced in the serum of COVID-19 acute patients [6] and in pediatric post-COVID vasculitis [7]; and (iii) vascular endothelial growth factor A (VEGF-A), a biomarker of pathological neo-angiogenesis [20].