Researchers aiming to block excessive lung inflammation in COVID-19 patients found upregulated immune checkpoint biomarkers in patients with a range of COVID-19 symptoms (from paucisymptomatic to acute respiratory distress syndrome). In addition, Carvelli et al. found increased expression of C5a, an inflammatory mediator, in serum and the C5aR1 receptor on myeloid cells in COVID-19 patients, which are known to initiate inflammatory responses by recruiting neutrophil and monocytes to lungs. An in vitro neutrophil migration assay quantified with the CytoNuclear FL Module of HALO software demonstrated that the clinical stage therapeutic monoclonal antibody, avdoralimab, effectively inhibited C5a-induced neutrophil migration. The authors propose use of avdoralimab to limit excessive lung inflammation associated with acute respiratory distress in COVID-19 patients.