Post-failure Stepwise Heat-Denaturated Protein Introduction for Tolerance Induction in Cow's Milk Allergy Observational Cohort Study

In this observational study the investigators will study the time to complete tolerance in cow's milk allergic children who tolerate 20' heated milk but failed the OFC with unheated milk 12 months after passing the 20' boiled cow's milk OFC. Moreoever, the investigators want to document all clinical reactions and potential cofactors during the tolerance induction process. The investigators anticipate that the whole cohort will become tolerant in a time span shorter than 48 months. Therefore the study period in each participant will be 48 months or the period to achieve complete tolerance (which comes first).

Inclusion criteria

Participants eligible for inclusion in this study must meet all of the following criteria:

• participation in s68299
• failure to challenge test with unheated cow's milk
• passed challenge test with unheated cow's milk but with symptoms developing between challenge and termination visit related to cow's milk intake at home

Exclusion criteria

Participants eligible for this study must not meet any of the following criteria:

• Subjects not priorly enrolled in s68299
• Subjects enrolled in s68299 who passed the challenge test and have no complaints upon regular cow's milk consumption at termination visit
• Subjects who refuse to consent/assent with the study