In module 2, mono-CD14+ cells in patients with severe COVID-19 exhibited higher expression levels of glycolysis-related genes (LDHA and PKM) and PPP-related genes (PGD and TKT), which may be involved in the proinflammatory response (upregulation of S100A8, S100A9, S100A12, and IL1B) (Figures 3C, E). Here, PGD is linked to COVID-19.