France is a low-endemicity country for hepatitis B virus (HBV) infection. In 2016, the prevalence of chronic HBV infection in the general population was estimated at 0.3%, corresponding to more than 135,000 HBsAg-positive individuals, of whom 82% were unaware of their infection. Data on hepatitis D virus (HDV) infection remain limited; however, available studies suggest a prevalence of 6% to 10% among HBsAg-positive individuals. Despite current guideline recommendations, up to 35% of newly diagnosed HBsAg-positive patients between 2018 and 2022 were not screened for HDV infection.

The World Health Organization (WHO) targets for 2030 include a 90% reduction in the incidence of chronic viral hepatitis, a 65% reduction in hepatitis-related mortality, and treatment coverage for 80% of eligible diagnosed individuals. Achieving these goals will require strengthening HBV and HDV screening strategies and improving linkage to care and retention throughout the care cascade.

Objectives: The primary objective is to assess the severity of liver disease, including significant fibrosis (≥F2) and cirrhosis (F4), among adults newly diagnosed with chronic HBV infection (with or without HDV infection) at Expert/Reference Hepatology Centers and Hepatology or Infectious Diseases Departments.

The secondary objectives are to:

1. Describe demographic and virological characteristics of HBsAg-positive patients;
2. Determine the proportion of patients eligible for HBV treatment and evaluate treatment response at 6 and 12 months;
3. Assess the utility of novel virological markers for classifying patients according to phases of chronic HBV infection;
4. Evaluate HBsAg thresholds, in combination with other markers, for distinguishing HBeAg-negative chronic infection from HBeAg-negative chronic hepatitis;
5. Compare clinical and virological characteristics of HBV-monoinfected and HBV/HDV-coinfected patients;
6. Identify molecular signatures associated with liver disease severity;
7. Compare findings with those of a national cohort conducted 15 years earlier;
8. Collect biological samples for future analyses;
9. Assess the clinical utility of a highly sensitive HBcrAg assay. Method: This is a multicenter, observational study including all adults aged ≥18 years with chronic HBV infection, whether managed as outpatients or inpatients, who are newly referred to Expert/Reference Hepatology Centers or to Hepatology or Infectious Diseases Departments.

Conclusions: This study will generate updated national data on liver disease severity, treatment eligibility, and virological characteristics among adults newly diagnosed with chronic HBV infection in France.