CCL2 and lymphopenia: Immunological studies in patients expressing severe COVID-19 symptoms, revealed lymphopenia—a clinically severe reduction of white blood cells in blood [70]—and an increased level of interleukin (IL)-6, IL-10, proinflammatory cytokines, as well as Granulocyte-Colony Stimulating Factor (G-CSF), Monocyte Chemoattractant Protein-1 (MCP-1), Tumor Necrosis Factor-α (TNFα), and Macrophage Inflammatory Protein-1α (MIP-1α) [69].