In addition, all T and NK subpopulations enriched with increasing severity showed high expression of negative regulators of apoptosis (Supplementary Data 6), including various subsets of the following genes: BCL2, BCL3, PIM1, PIM2, MYC, DDIT4 and XBP1. In summary, high-resolution differential cell state analysis within T and NK cells revealed multiple SOCS3-high subpopulations that may contribute to the suppression of type I IFN response observed in severe COVID-19. Here, XBP1 is linked to COVID-19.