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

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