Infectious Bursal Disease (IBD), Newcastle Disease (ND), and low-pathogenic Avian Influenza (H9) pose significant economic threats to the global poultry industry. Despite widespread vaccination efforts, outbreaks of highly virulent Infectious Bursal Disease Virus (vvIBDV) continue, leading to uncertainty about optimal vaccination strategies, especially regarding the synergistic effects of combined vaccines and the relative effectiveness of domestic versus international formulations. This study evaluated the humoral immune response and protective efficacy of different vaccination protocols, comparing international triple-inactivated vaccines (H9 + ND + IBD) with domestic formulations, administered with or without an additional live intermediate IBD vaccine. A total of 180 Ross-308 broiler chickens were divided into six experimental groups. Inactivated vaccines were administered on Day 8, followed by live intermediate Gumboro vaccination on Days 17 and 24 when applicable. All groups were challenged with vvIBDV on Day 35. Vaccine efficacy was assessed using ELISA and HI serology, viral load quantification in the bursa of Fabricius by RT-qPCR (C_t values), and histopathological evaluation of lymphoid depletion. The highest level of protection was observed in broilers receiving the international inactivated vaccine combined with a live intermediate vaccine, characterized by a strong humoral response (ELISA titer = 4153) and markedly reduced viral replication (C_t = 44.06). Notably, although the international inactivated vaccine alone provided substantial protection (ELISA titer = 4577), adding a live vaccine did not yield a statistically significant improvement (P > 0.05), suggesting that high-potency inactivated antigens may independently provide effective protection. Conversely, domestic Iranian vaccine formulations induced significantly lower immunogenicity and higher bursal lesion scores, revealing a pronounced efficacy gap compared to international products. These findings indicate that although combined live-inactivated vaccination strategies provide broad protection, the overall success of vvIBDV control programs is largely determined by the antigenic mass and the quality of the inactivated vaccine formulation. Enhancing the potency and consistency of domestic vaccines is therefore essential to achieve effective and sustainable control of vvIBDV in endemic regions.