Review Persistent airway obstruction in severe eosinophilic asthma: targeting interleukin-5 and eosinophils Article Figures & Tables Info & Metrics Introduction Asthma is a chronic, inflammatory disease of the airways, currently estimated to affect 300 million people globally [1]. Asthma is typically characterised by airway hyperresponsiveness, chronic airway inflammation and reversible airway obstruction, which can become persistent [1].