Immunological changes generally observed in patients with COVID-19 include lymphocytopenia that pertains to CD4+, CD8+, and Treg cells and increased levels of proinflammatory cytokines [e.g., interleukin (IL)1-β, IL-1RA, IL-7, IL-8, IL-9, IL-10, interferon (IFN)γ, interferon-gamma induced protein (IP)10, monocyte chemoattractant protein (MCP)1, macrophage inflammatory protein (MIP)1α, MIP1β, tumor necrosis factor (TNF) α, granulocyte colony stimulation factor (GCSF), platelet derived growth factor (PDGF) B, and vascular endothelial growth factor (VEGF) A]. Here, CD4 is linked to COVID-19.