Interestingly, a similar observation was made in the BAL from patients with COVID-19, where most BAL infiltrates expressed CXCR3 and/or CXCR4 (Liao et al., 2020), and the increased presence of activated lung-homing CXCR4+ T cells was associated with fatal COVID-19 (Neidleman et al., 2021). Here, CXCR4 is linked to COVID-19.