Prevention od new sensitization by sublingual immunotherapy in children 2-4 years of age with allergic mono-sensitization

INTERVENTION: Trade Name: Novo Helisen oral Pollen Pharmaceutical Form: Oral drops* Pharmaceutical form of the placebo: Oral drops* Route of administration of the placebo: Sublingual use Trade Name: Novo Helisen oral Hausstaubmilbe Pharmaceutical Form: Oral drops* Pharmaceutical form of the placebo: Oral drops* Route of administration of the placebo: Sublingual use CONDITION: Children (2‐4years of age) from atopy prone families with an allergic sensitization as defined by positive skin prick test or positive allergen‐specific IgE to grass pollen or house dust mite allergen without presence of manifest allergic disease PRIMARY OUTCOME: Main Objective: The pupose of the trial is to test whether sublingual immunotherapy applied in children with monosensitization to either house dust mite or grass pollen allergens can prevent the development of new sensitizations in the following 2 years (secondary prevention) Primary end point(s): primary end point of the study is the assessment of new sensitizations in skin prick test or allergen‐specific IgE‐antibody detection during the 2 year sublingual treatment period Secondary Objective: INCLUSION CRITERIA: ‐ children of age 2‐4 years (>24 month of age) ‐ positive family history for allergic diseases ‐ presence of positive skin prock test reactivity and/or allergen‐specific IgE‐antibodies to either house dust mite allergen or grass pollen allergen ‐ optionally symptoms indicative of asthma/wheezing bronchitis and rhinitis without persistent treatment need in the last 6 months ‐ optionally atopic dermatitis in the subjects own history Are the trial subjects under 18? yes Number of subjects for this age range: F.1.2 Adults (18‐64 years) no F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) no F.1.3.1 Number of subjects for this age range