IL7 and lymphopenia: Accumulating evidence suggests that deregulation of myeloid cell-mediated responses potentially triggers lymphopenia, cytokine release syndrome, acute respiratory distress syndrome (Mehta et al., 2020), and pathogenic inflammation with high level secretion of IL-6, IL-2, IL-7, IFN-ɣ, IFN-I, and type III IFNs (Shi et al., 2019) in COVID-19 patients with severe clinical manifestations.