IL‐33 is known to drive Th‐2 responses and play a crucial role in allergy and lung‐related inflammatory conditions.44 Our novel findings in relation to IL‐31 and IL‐33 warrant further investigation in a larger cohort of alloHSCT recipients as these may serve as biomarkers that can be used for risk prediction of Aspergillus infections post‐alloHSCT. This evidence concerns the gene IL31 and allergic disease.