6. Any condition requiring systemic treatment with either corticosteroids (>10mg daily prednisone or equivalent dose of alternative corticosteroid) or other immunosuppressive medications within 14 days of registration. Intranasal, inhaled or topical steroids are permitted in the absence of active autoimmune disease. Participants are permitted to enrol if they have vitiligo, type I diabetes mellitus, residual hypothyroidism due to autoimmune condition only requiring hormone replacement, psoriasis not requiring systemic treatment, or conditions not expected to recur in the absence of an external trigger.