Long-Term PF-06651600 for the Treatment of Alopecia Areata

Inclusion Criteria- For de novo participants and participants from Study B7931005 and B7981015 with \>30 days between first visit in B7981032 and last dose in the prior study: * Clinical diagnosis of alopecia areata (AA) with no other cause of hair loss. Androgenetic alopecia coexistent with AA is allowed. * De novo participants \>=12 to \<18 years of age: \>=50% terminal hair loss of the scalp due to AA, including alopecia totalis and alopecia universalis * De novo participants \>=18 years of age and participants from Study B7931005 or B7981015 with \>30 days between first visit in B7981032 and last dose in the prior study: \>=25% terminal hair loss of the scalp due to AA, including alopecia totalis and alopecia universalis * No evidence of terminal scalp hair regrowth within 6 months (de novo only) * Current episode of terminal scalp hair loss \<=10 years (de novo only) Exclusion Criteria- For de novo participants and participants from Study B7931005 and B7981015 with \>30 days between first visit in B7981032 and last dose in the prior study: * Hearing loss with progression over previous 5 years, or sudden hearing loss, or middle or inner ear disease, or other auditory condition that is considered acute, fluctuating or progressive * History of or current malignancies with the exception of adequately treated or excised non metastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ * History of a single episode of disseminated herpes zoster o…