IL6 and COVID-19: In contrast, respiratory samples from non-COVID-19 ICU patients showed significantly higher levels of several cytokines, including IL-6, IL-6:sIL-6Ra ratio, IL-1b, IL-8, IL-10, IL-18, IL-23, TNF, MCP-1 compared to matched plasma samples (7–440× higher) (Fig. 2a, Supplementary Fig. 1b), reflecting consistent levels of those cytokines across non-COVID-19 ICU patients.