 Birch pollen allergic patients are currently treated by subcutaneous injections of pollen extracts either by standard allergen specific immunotherapy SIT or ultra-rush immunotherapy. Such treatment is prone to side effects and has to be performed in a hospital environment due to the risk of potential anaphylactic reactions. The aim of this study is to test the new product AllerT expected to show widely reduced side effects. AllerT will be injected via two different routes, subcutaneous versus intradermal. The primary endpoint of the study is the local and systemic safety of repeated injections of the product. Since AllerT should provide patients with a pre-seasonal treatment to decrease seasonal allergic symptoms, we will also evaluate the potential efficacy of the approach using a nasal provocation test NPT with birch pollen 