This is a Phase 2b/3 study designed to evaluate the safety and efficacy of chronic treatment with brelovitug (a.k.a BJT-778; BTG) for chronic hepatitis delta virus (HDV) infection. The comparator in this study will be 24-weeks of delayed treatment. During the 24-weeks of delayed treatment, participants will complete the same visits and assessments as those randomized to initiate brelovitug immediately. At the completion of 24-week delayed treatment period, all participants will start treatment with brelovitug.