CXCL9 and COVID-19: The definition of these target gene sets, including GZMB, IFNG, TNF, CCL3, and CCL4 in stimulated reactive CD4 T cells, led to the prediction of macrophage-derived co-stimulatory ligands such as IL-15, IL-18, CCL4, CCL8, or CXCL9, which have been described to be upregulated in macrophages from the respiratory tract during COVID-19 also in the original studies on the Berlin and Shenzhen cohorts47,48 (Supplementary Fig. 15).