MPO and COVID-19: A study of COVID-19 patients with non-severe (NS), severe (S), and acute phase (PAP) disease found that the diagnostic power of NE and MPO (markers of NETs) as determined by the area under the subject operating curve (AUROC) was greater than 0.94, especially the diagnostic power of MPO in both severe (S) and acute phase (PAP) groups was shown to be 100%.