Study design
MAY
This was a single-center, double-blinded, randomized, placebo-controlled trial treating two groups in parallel. The study was performed over 3 weeks starting just prior to the birch pollen peak of the season in April to May 2019 (Fig. Study outline.The study was approved by the National Research Ethics Committee and was conducted according to good clinical practice guidelines. All methods were performed in accordance with national guidelines and regulations as well as the Declaration of Helsinki. All participants provided written informed consent. The trial was registered (04/12/2018) in the EudraCT database as no. 2018-004205-12 and in the register of ClinicalTrials.gov (first posted 10/11/2020 and last release 24/06/22) with identifier NCT04622917. All data generated or analyzed during this study are included in this published article (se supplementary information files).