CCL2 and COVID-19: Consistently, the metatranscriptomic sequencing of the BALF discovered that COVID-19 patients showed marked hypercytokinemia and up-regulated IFN-stimulated genes, especially significantly elevated expression of chemokines, such as CXCL17, CXCL8, CCL2, and CCL7 (Zhou Z. et al., 2020).