This observational research study is to better understand patients with eosinophilic esophagitis (EoE) who have recently been prescribed DUPIXENT® (dupilumab). The purpose of this research study is to look at how DUPIXENT is used in normal care of patients with EoE.

Possible benefits to others include a better understanding of EoE and helping to inform research and clinical trial design leading to treatment decisions in this patient population going forward.

This is a randomized, double-blind, multicenter, parallel-group Phase IIIb study with a fixed treatment period of 52 weeks. The purpose of this study is to compare BDA MDI with AS MDI on severe asthma exacerbations in adolescent participants aged 12 to < 18 years with a documented clinical diagnosis of asthma and at least one severe exacerbation in the prior year. Participants will administer randomized IMP as needed as they normally would with their own prescribed rescue inhaler.