CCL2 and COVID-19: Nonetheless, COVID-19 patients with disease progression present with abnormal immune profiles, including sustained high levels of circulating proinflammatory factors (IL-6, IL-1β, IL-2, IL-8, IL-17, IL-18, IL-22, G-CSF, GM-CSF, IP10, MCP1, MIP1α, and TNF-α, etc.)(22, 38–41), known as a “cytokine storm,” as well as lymphopenia (involving reduced numbers of CD4+ T cells, CD8+ T cells, and NK cells) (22, 40) with the remaining T and NK cells tending to exhibit reduced functional diversity and a more exhausted phenotype (34, 42, 43).