IL9 and COVID-19: We found that acute COVID-19 neutrophils secreted reduced G-CSF, MIP-1α, MIP-1β, MCP-1, IL-2, SDF-1α, IL-9, IL-17A, IL-18, IL-20 and IL-23 levels, but secreted increased soluble PD1, IP-10 and MIP-2α levels compared to rec-phase and healthy neutrophils upon bacterial challenge (Fig 5J–5K).