Table 2.

Possible path toward prophylactic vaccination with molecular allergy vaccines.

Step	Type of study	Possible study endpoints	Possible favorable outcomes
Step 0	Therapeutic vaccination of allergic patients	Safety. Induction of allergen-specific IgG blocking antibodies. Boosting of allergen-specific IgE responses. Induction of allergic sensitization Reduction of symptoms	Safe Induction of high levels of allergen-specific IgG without boosting allergen-specific IgE production. No induction of clinically relevant allergic sensitization. Reduction of symptoms
Step 1	Vaccination of non-allergic subjects	Safety. Induction of allergen-specific IgG blocking antibodies. Induction of allergic sensitization. Appearance of symptoms of allergy	Safe Induction of high levels of allergen-specific IgG inhibiting allergic patients IgE binding to allergens. No induction of clinically relevant allergic sensitization
Step 2	Secondary preventive vaccination of sensitized children	Safety. I Prevention of transition of mild allergic symptoms toward severe symptoms. Effects on symptoms II. Prevention of transition of clinically silent IgE sensitization to symptoms. Development of symptoms	Safe. I. Prevention of progression of mild toward severe symptoms II. Prevention of progression of clinically silent IgE sensitization to symptoms of allergy
Step 2	Prenatal vaccination of mothers	Safety. Induction of allergen-specific IgG in mothers. Prevention of allergen-specific IgE sensitization in off-springs	Safe Induction of allergen-specific IgG in mothers. Prevention of allergen-specific IgE sensitization in off-springs
Step 3	Early postnatal primary preventive vaccination of not yet sensitized children	Safety. Prevention of allergen-specific IgE sensitization. Induction of allergen-specific IgG	Safe Induction of allergen-specific IgG capable of inhibiting IgE binding to allergen. No induction of clinically relevant allergic sensitization. Prevention of allergen-specific IgE sensitization