• Enrollment will be fully sequential by age group, with adolescents (12 to less than 18 years old) enrolling before children (6 to less than 12 years old).

• Have severe areata alopecia (AA) for at least 1 year

• Diagnosis for at least 1 year

• Current AA episode of at least 6 months' duration

• SALT score ≥50% at screening and baseline

• History of trial and failure with at least 1 available treatment (topical or other) for AA

• History of psychological counseling related to AA

• Current episode of severe AA of less than 8 years.

⁃ Note: Participants who have severe AA for ≥8 years may be enrolled if episodes of regrowth, spontaneous or under treatment, have been observed on the affected areas over the past 8 years.