A Study to Evaluate the Safety and Effectiveness of Upadacitinib in Pediatric Participants With Alopecia Areata

Inclusion Criteria: * Participants must have a diagnosis of severe alopecia areata with SALT score \>= 50 scalp hair loss at Screening and Baseline * No spontaneous scalp hair regrowth over the past 6 months * Participants will have current episode of alopecia areata of less than 8 years Exclusion Criteria: * Participants must not have a current diagnosis of primarily diffuse type of alopecia areata * Participants must not have a diagnosis of other types of alopecia that would interfere with evaluation of alopecia areata, including but not limited to female pattern hair loss, male pattern hair loss (androgenetic alopecia) Stage III or greater, traction alopecia, lichen planopilaris, discoid lupus, frontal fibrosing alopecia, central centrifugal cicatricial alopecia, folliculitis decalvans, trichotillomania, and telogen effluvium * Participants must not have a diagnosis of other types of inflammatory scalp, eyebrow, or eyelash disorders that would interfere with evaluation of alopecia areata, including but not limited to seborrheic dermatitis, scalp psoriasis, AD, and tinea capitis