MPO and COVID-19: The upregulation of MPO and PRTN3 was significantly higher in severe versus mild COVID-19 (MPO, 3.4 ± 0.3 vs 1.9±0.3 log fold change [LogFC]; p-value = 0.004, and PRTN3 (2.9 ± 0.5 vs 1.6 ± 0.5 LogFC; p-value = 0.01 as presented in Figure 1C).