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Introduction Hepatitis delta virus (HDV) remains an underdiagnosed cause of severe liver disease in patients with chronic hepatitis B (CHB). Variable testing practices can delay diagnosis and access to treatment. We implemented a double- reflex testing pathway at Barts Health NHS Trust, where all hepatitis B surface antigen (HBsAg)-positive patients automatically undergo HDV antibody (HDV Ab) testing, with reflex HDV RNA testing for HDV Ab- Positive cases. The aim was to accelerate HDV case- finding and streamline linkage to specialist care, including access to licensed therapy, bulevirtide (BLV), and recruitment into clinical trials of novel therapies for HDV.Methods Double- reflex HDV testing was rolled out across all sites at Barts Health NHS Trust (Royal London, Whipps Cross, Newham, and St Bartholomew’ s Hospitals). HBsAg- positive patients underwent reflex HDV Ab testing. HDV Ab- Positive samples triggered automatic reflex HDV RNA testing, achieving ≥99% compliance. Patients with detectable HDV RNA were promptly referred to specialist hepatology services for treatment assessment, including eligibility for BLV and clinical trial enrolment.Results In total, 7, 218 HBsAg- positive patients underwent reflex HDV Ab testing. Of those screened, 458 (6. 3%) were HDV Ab- positive, and 168 (2. 3%) had confirmed active HDV infection with detectable HDV RNA. Demographically, the population was predominantly male (85%), of Eastern European background, with a median age of 38 years (IQR = 6) and variable ALT and HDV RNA levels ( figure 1). Following identification, patients were streamlined into management pathways. Currently, 48 (29%) patients are being assessed for BLV, 19 (11%) are receiving BLV, 17 (10%) are enrolled in HDV clinical trials, and 84 (50%) of newly identified HDV RNA- positive patients are either not eligible for BLV (n = 23, 14%) or awaiting specialist clinic review (n = 61, 36%). Our cohort showed no significant difference in HDV RNA reduction between patients treated with BLV and those enrolled in HDV clinical trials, matched at 6 months (P = 0. 774), with follow- up ongoing.Conclusion Large- scale double- reflex testing successfully embedded HDV detection into routine CHB care across East London, identifying substantial numbers of HDV patients and reducing delays to specialist review and treatment access. Reflex testing has facilitated access to both licensed therapy (BLV) and clinical trials of novel agents. This approach is scalable and could serve as a model for wider NHS adoption to improve access to HDV diagnosis and treatment nationally.Abstract P75 Figure 1ALT and HDV RNA levels in HDV RNA-positive patients