CCL2 and COVID-19: Several biomarkers, such as procalcitonin (Liu et al., 2020; Khodeir et al., 2021), C-reactive protein (Liu et al., 2020; Khodeir et al., 2021), interleukin-6 (IL-6) (Jørgensen et al., 2020; Liu et al., 2020; Khodeir et al., 2021), and monocyte chemotactic protein-1 (MCP-1) (Chen et al., 2020; Jørgensen et al., 2020) have been found to be associated with prognosis or disease severity in patients with COVID-19.