CXCR3 and influenza: To analyze lung-homing capacities of NK cells and T cells during acute respiratory viral infections, we first determined the expression of chemokine receptors relevant for lung-homing (CXCR3, CXCR6, CCR2, CCR5) on NK and T cell subsets in peripheral blood from COVID-19 and influenza patients as well as healthy controls (Figure 1; see Figure S1A for gating strategy).