Findings by Ren and colleagues are consistent with our recent publication implicating inflammatory macrophages and neutrophils in severe COVID-19.3 During the disease progression stage of severe COVID-19 patients, Ren et al. reported S100A9 and S100A8 to be significantly up-regulated in the majority of cell clusters in PBMCs and BALF. The gene discussed is S100A8; the disease is COVID-19.