House Dust Mite Allergy Trial In Children

Inclusion Criteria: * Male or female subjects aged 5-11 years * A clinical history of HDM AR/C (Allergic rhinitis/rhinoconjunctivitis) (with or without asthma) and with allergic rhinitis symptoms despite having received allergy pharmacotherapy during the previous year prior to screening * Have a certain level of AR (Allergic rhinitis) symptoms on at least 8 of the last 14 days of the baseline period * Use symptomatic medication for treatment of HDM allergic rhinitis during at least 8 of the last 14 days of the baseline period * Positive skin prick test (SPT) and IgE (Immunoglobulin E) to D. pteronyssinus or D. farinae at screening * Lung function ≥ 70% of predicted value Exclusion Criteria: * Sensitised and regularly exposed to perennial allergens * Any nasal or pharyngeal condition that could interfere with the safety or efficacy evaluation * Asthma requiring treatment with high dose of inhaled corticosteroid * A relevant history of systemic allergic reaction