CCL2 and COVID-19: In fact, it has been reported that IL-6 (2, 40, 41), eotaxin (42), IL-1RA (43), I-TAC (44), and MCP-1 (45), which were elevated in CMs after the initial infection, are also involved in aggravation in humans, and our CM COVID-19 model could be used in future pathological studies related to these factors.