In published datasets comprising PBMC samples from patients with COVID-19 (7, 28, 29, 31), we found that increased expression of the MS1 gene program in monocytes consistently correlated with lower CD8 T cell fractions in each of the four datasets that we analyzed (P < 0.05 in two of four datasets; Fig. 4D) and less so with CD4 T cells (P < 0.05 in one dataset) (49). Here, CD4 is linked to COVID-19.