MPO and COVID-19: Recent studies have documented alterations in oxidative bursts, phagocytic function, and reduced myeloperoxidase (MPO) activity in neutrophils collected from critically ill COVID-19 patients, yet these descriptive interpretations do not yet elucidate the mechanisms underlying neutrophil dysfunction and the complex interplay between virus-induced immune dyscrasias and COVID-19 disease progression [6,13,15].