Fig. 1: Neutrophils in disease.

During a respiratory viral infection, neutrophils are recruited to and activated in the lung. In non-symptomatic or mild disease, neutrophil numbers peak early during infection and neutrophils exert their effector functions and aid in tissue repair and resolution of inflammation. In a severe infection, more neutrophils are recruited over a longer period. This results in more tissue damage and a delay or block in resolution of inflammation and tissue repair.