CCL2 and COVID-19: Early in the pandemic, it already became clear that circulating levels of numerous inflammatory cytokines, such as interleukin (IL)-1β, IL-8, IL-6, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ-inducible protein 10 (IP-10), granulocyte macrophage-colony stimulating factor (GM-CSF), and monocyte chemoattractant protein-1 (MCP-1) were increased in patients with SARS-CoV-2 infection15.