Around 254 million people worldwide are infected with the hepatitis B virus (HBV). As a result, over one million people die each year from liver failure or liver cancer. Current therapies suppress the virus, but they do not cure it. The DZIF TherVacB project is developing an immunotherapy that activates the immune system to control or eliminate the virus. The TherVacB vaccine is effective against over 95 percent of the HBV strains found worldwide. After a successful Phase Ia clinical trial, a European multicenter Phase Ib/IIa trial began in June 2025 to evaluate the vaccine's safety and efficacy in patients.