Zheng et al. highlighted that individuals grappling with severe COVID-19 presented elevated CD4+ T-cell levels but diminished secretion of interferon-γ, interleukin-2, and tumor necrosis factor-α compared to both healthy individuals and moderate case counterparts.21 Additionally, these patients exhibited increased levels of CD8+ T-cells expressing HLA-DR and T-cell immunoreceptors with Ig and ITIM domains. This evidence concerns the gene IL2 and COVID-19.