Considering that high levels of blood eosinophils may be masked by chronic OCS use and that in OCS-dependent severe asthma patients an underlying (ANCA-negative) eosinophilic granulomatosis with polyangiitis (EGPA) has always to be suspected, a serial assessment of blood eosinophil counts during treatment with an anti-IL-4/IL-5 biologic seems advisable. This evidence concerns the gene IL4 and asthma.