A Study to Identify and Characterize Adults and Pediatric Participants With Cat and/or Birch Allergy

Key Inclusion Criteria: 1. Adults or pediatric participants, ≥5 years of age inclusive (pediatric participants ≥5 years and \<18 years and weighing ≥10 kg, to be enrolled where permitted per local regulations/approvals), at the time of signing the informed consent 2. Participant-reported (and/or caregiver-reported for pediatric participants) and/or documented allergic history as described in the protocol 3. Positive Skin Prick Test (SPT) at screening: to cat allergen (Part A) and/or to birch allergen (Part B) 4. Must not currently live with a cat(s) or have lived with a cat(s) in the home for the past 1 year (Part A) 5. Willing and able to comply with clinic visit(s) and study-related assessments Key Exclusion Criteria: 1. Presence of any ophthalmic disease/abnormality/condition that may interfere with study assessments, affect the study outcomes or participant safety as described in the protocol 2. History of life-threatening asthma, defined as an asthma episode that required intubation and/or was associated with hypercapnia, respiratory arrest, and/or hypoxic seizures 3. Active, chronic infections requiring long-term use of systemic antibiotics, antivirals, or anti-fungal treatments Note: Other Protocol Defined Inclusion/ Exclusion Criteria Apply