Unexpectedly low prevalence of hepatitis delta virus infection in Southern Viet Nam

Viet Nam faces a significant burden of viral hepatitis-associated liver disease, but the contribution of HDV, the most severe form of viral hepatitis, remains underinvestigated. HDV is substantial in the Northern and Central regions, but has not been documented in the South of Viet Nam. To investigate HDV prevalence and its association with severe liver disease in Southern Viet Nam, we used the standardized assay (LIAISON XL Anti-HDV) to detect HDV antibodies (anti-HDV) in 721 HBsAg positive individuals with hepatitis flare (n = 158), liver cirrhosis (LC) (181), hepatocellular carcinoma (HCC) (207), chronic hepatitis B (CHB) (175). Unexpectedly, anti-HDV was rare and only detected in 11/721 participants (1.5%), and not significantly different among groups: 2/158 (1.3%) in flare, 4/181 (2.2%) in LC, and 5/207 (2.4%) in HCC, and 0/175 (0%) in CHB. This suggests that HDV is not one of the major contributors to the high burden of liver disease in Southern Viet Nam. The discrepancy of HDV prevalence between Northern-Central and Southern regions suggests location-specific distribution of HDV, which in turn reflects differences in HDV transmission routes, study populations, and/or study methodologies. Our study underscores the need for tailored, regional screening strategies rather than a single national guideline for HDV infection.