Trapsgewijze Ei-tolerantie-inductie Bij Kippenei-allergische Kinderen (TETI Studie)

1. The investigators here want to test the hypothesis that a total period of 18 months of gradual open introduction of a certain egg product with regard to full egg tolerance induction is not inferior when compared to a total period of 30 months gradual open introduction of a certain egg product (see steps for the specific egg products) after tolerance to baked egg has been obtained.
2. The investigators also want to define step-specific 'tolerance-failures' and study the relevance of specific IgE to specific egg components to predict failures at each step.

Step 1: open baked egg test passed (either at home or in the hospital): this is routine clinical practice; afterwards daily intake of increasing amounts of heated egg (amounts to be noted in diary)

Step 2: open provocation test at home with hard-boiled egg, both hen's egg white and yolk, passed; afterwards weekly intake of either hard-boiled egg white or yolk or both (amounts and days to be noted in diary)

Step 3: open provocation test at home with waffles, omelet, pan cake or scrambled egg passed; afterwards weekly or two-weekly intake of one of these specific preparation forms or of the previous preparation forms (amounts, days and preparation to be noted in diary)

Step 4: open provocation test at home with fried or poached egg or softly boiled egg with liquid yolk; afterwards regular intake of one of these preparation forms or one of the prior steps (amounts, days and preparation to be noted in diary)