Inclusion Criteria:
* A positive prick skin test (PST) with a wheal ≥ 6 mm to at least two of the relevant foods (peanut, cashew, walnut, egg, or milk)
* Positive food specific IgE (≥2.0 kUA/L) to at least two of the relevant foods
* A positive history of clinical reaction to at least one of the qualifying foods other than the challenge-qualifying food
(If meeting above criteria):
* Positive oral food challenge (OFC) to one of the potentially qualifying foods at a cumulative dose of ≤144 mg (maximum tolerated dose ≤30 mg)
Exclusion Criteria:
* Weight \>80 kg at time of screening
* Clinically significant laboratory abnormalities at screening.
* Sensitivity or suspected/known allergy to any ingredients (including excipients) of omalizumab.
* Poorly controlled or severe asthma/wheezing at screening
* History of severe anaphylaxis to participant-specific foods that will be used in this study, defined as neurological compromise, PICU admission f for continuous epinephrine for hypotension or severe respiratory compromise requiring intubation.
* Treatment with a burst of oral, intramuscular (IM), or intravenous (IV) steroids of more than two days for an indication other than asthma/wheezing within 30 days of screening.
* Currently receiving oral, IM, or IV corticosteroids, tricyclic antidepressants, or β-blockers.
* Past or current history of eosinophilic gastrointestinal disease within three years of screening.
* Past or current history of cancer, or currently being investigated for possible cancer.
* Past or current history of any food immunotherapy (e.g., OIT, SLIT, EPIT) within 6 months of screening.
* Treatment with monoclonal antibody therapy, or other immunomodulatory therapy within 6 months of screening.
* Inability to discontinue antihistamines for minimum wash-out periods required for SPTs or OFCs.
* Pregnant or breastfeeding or intending to become pregnant during the study.
* Evidence of clinically significant chronic disease.
