CCL2 and lymphopenia: Patients with severe and critical COVID-19 have high systemic levels of inflammatory molecules, predominantly interleukins (IL-2, IL-6, IL-10), interferon- γ (IFN-γ) inducible protein 10 (IP10), monocyte chemoattractant protein 1 (MCP-1), granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-α) along with lymphopenia.