Hepatitis D is by far the most severe form of chronic viral hepatitis, frequently leading to liver failure, hepatocellular carcinoma and death. Hepatitis D is caused by coinfection Hepatitis D is caused by co-infection with hepatitis B virus (HBV) and hepatitis D virus (HDV). This multicenter cohort should enable a comprehensive and unbiased biomarker screening of well-defined HDV-infected patients, followed by mechanistic studies to determine the functional role of distinct molecules. Patient surveillance strategies and antiviral treatment approaches could be personalized which should reduce clinical and social disease burden, improve quality of life and save direct and indirect costs caused by HDV infection.