[Vaccines against hepatitis E virus: state of development]

Area of Science:

• Virology
• Vaccinology
• Immunology

Background:

• Currently, no vaccine against the hepatitis E virus (HEV) is licensed in Europe.
• HEV-239 (Hecolin®) has been available in China for a decade, targeting HEV genotype 4.
• HEV vaccine development faces challenges due to genotype diversity, transmission routes, risk groups, viral mechanisms, and immune responses in vulnerable populations.

Purpose of the Study:

• To review the current status of available and preclinical HEV vaccines.
• To focus on vaccine development strategies, challenges, and limitations.
• To discuss future directions for HEV vaccine research and development.

Main Methods:

• Review of current literature on HEV vaccines.
• Analysis of vaccine development strategies, including protein-based immunization and monoclonal antibodies.
• Evaluation of clinical trial data and preclinical studies.

Main Results:

• Protein-based vaccine candidates aim to induce neutralizing antibodies.
• The HEV-239 trial focused on preventing symptomatic infections, with unclear efficacy against asymptomatic cases or in high-risk groups (e.g., cirrhosis, immunosuppression, pregnancy).
• In vitro models are advancing monoclonal antibody development for passive immunization.

Conclusions:

• Future HEV vaccines require broad genotype coverage and excellent safety profiles.
• Developing effective passive immunization strategies, particularly for immunosuppressed individuals, is crucial.
• Further research is needed to address HEV vaccine efficacy in diverse populations and against all genotypes.