Arguing against an unusually severe inflammatory response or “cytokine storm” in patients with COVID-19, the concentrations of other BAL fluid cytokines in samples collected during the first 48 hours of intubation, including CXCL1, IFN-γ, IL-1β, IL-6, IL-8, and TNF-α, were higher in patients with pneumonia relative to healthy controls but were largely similar between groups of mechanically ventilated patients (complete comparisons are included in Supplemental Data 7). Here, CXCL1 is linked to susceptibility to pneumonia measurement.