Box 12. Recommendation.

All hypersensitivity reactions suspected of being associated with BLA should undergo diagnostic investigation at any age: on the one hand to identify the trigger and, if possible, the pathomechanism, while on the other, to prevent unnecessary avoidance of BLA by ruling out an allergy. In the case of positive and clinically relevant test findings, possible cross-allergies should be identified or ruled out in order to ensure that patients have access to future BLA treatments. As far as possible, this investigation should be performed within 1 year of the reaction. Prompt diagnosis is particularly important in the case of previous immediate reactions, since test reactivity diminishes over time.