CCL2 and COVID-19: Highest levels of circulating MCP-1 were found in older individuals with an unfavorable outcome (Figure 4B,C), indicating that MCP-1 levels not only increase with age (quadratic term, corresponding to a non-linear effect of age p = 0.034), but further increase in fatal COVID-19 cases (age- and time independent outcome effect corresponding to a general difference between groups p = 0.002, Contrasts: ICU vs. uncomplicated p = 0.004, death vs. uncomplicated p = 0.03).