(A) Schematic of the abnormal production of circulating macrophages and monocytes as well as changes in T cell subsets in peripheral blood from patients with COVID-19. (B) Peripheral blood monocytes/macrophages from healthy donor (upper left) and three COVID-19-positive patients (images reprinted with permission from Zhang D et al. MedRxiv preprint; doi: 10.1101/2020.03.24.20042655). (C) Time to hospital discharge of patients with COVID-19 who were stratified by levels of forward scatter in monocytes (reprinted with permission from Zhang D et al). (D) Comparison of IL-6, IL-10, IL-2, and tumor necrosis factor a levels in healthy controls and COVID-19-positive patients with mild versus severe disease; ***, p<0.001 (reprinted with permission from Shi Y et al. MedRxiv preprint; doi: 10.1101/2020.03.12.20034736).