CCL2 and COVID-19: Notably, we observed a significant correlation between the cross-disease shared CXCL10+ CCL2+ macrophages and two monocyte-derived alveolar macrophage (MoAM) inflammatory phenotypes from this independent severe COVID-19 cohort (wherein they were referred to as MoAM1 and MoAM2) [29] (Additional file 2: Figure S6a-d).