Inclusion Criteria:  Male or female of any race/ethnicity aged ≥4 to <18 years on the day informed consent is obtained from the parent/caregiver; the subject must be ≥5 to <18 years old at the randomisation visit A documented , physician diagnosed, clinically relevant history of moderate to severe AR/C induced by birch pollen (with or without asthma) despite having received treatment with symptom-relieving medication during at least 1 previous tree pollen season for ages 4 through 6 years at screening or at least 2 previous tree pollen seasons for ages 7 through 17 years at screening Positive skin prick test (SPT) to Betula verrucosa at screening Positive specific IgE to Bet v at screening  Presence of 1 or more of the following Allergic Rhinitis Impact on Asthma (ARIA) quality of life items due to AR/C during the previous BPS:  Sleep disturbance Impairment of daily activities, leisure and/or sport Impairment of school or work Troublesome symptoms  Exclusion Criteria:  A clinically relevant history of symptomatic seasonal AR/C caused by an allergen source, other than tree pollen from the birch homologous group, with a season overlapping the TPS A clinically relevant history of symptomatic perennial AR/C caused by an allergen source such as animal hair and dander to which the subject is exposed during the TPS Any clinical deterioration of asthma (i.e. asthma exacerbation) that resulted in emergency treatment, hospitalisation or treatment with systemic corticosteroids within 3 months prior to randomisation Reduced lung function at randomisation defined as forced expiratory volume in 1 second (FEV1) <70% of predicted value. For subjects with asthma, this is assessed on subject's usual asthma medication following at least a 6-hour wash-out of SABA. This criterion does not need to be fulfilled if the subject is <7 years old, cannot perform reproducible FEV1 manoeuvres despite coaching and is not considered as having a diagnosis of asthma Ongoing treatment with any allergy immunotherapy product Severe chronic oral inflammation A diagnosis of eosinophilic oesophagitis A relevant history of systemic allergic reaction e.g. anaphylaxis with cardiorespiratory symptoms, generalised urticaria or severe facial angioedema that in the opinion of the investigator may constitute an increased safety concern Immunosuppressive treatment (ATC code L04 or L01) within 3 months prior to the screening visit