MPO and COVID-19: More recently, the association of increased neutrophil–lymphocyte ratios (NLR) with ARDS8 and COVID-19-ARDS9 severity and poor prognosis, and increased bloodstream levels of NETs-associated myeloperoxidase-DNA complexes in COVID-19-ARDS10,11, further support the central role of neutrophils in ARDs-MOF.