[Vaccines against hepatitis E virus: state of development]

No vaccine against the hepatitis E virus (HEV) is currently licensed in Europe. In contrast, HEV-239 (Hecolin®, Xiamen Innovax Biotech Co., Xiamen, China), a vaccine against HEV genotype 4, has been available in China for 10 years. Challenges for the development of vaccines arise mainly from the differences between the genotypes with regard to distribution, transmission routes and risk groups. Other obstacles include the envelopment of HEV in blood by host membranes, replication in various organs outside the liver and weaker immune responses in vulnerable groups. This article reviews the current status of vaccines against HEV that are available and in advanced preclinical evaluation, with a focus on vaccine development strategies. Challenges and limitations are described.Current vaccine candidates focus on protein-based immunisation with the aim of inducing protective, neutralising antibody responses. The goal of the HEV-239 pivotal trial with more than 100,000 study participants was to prevent acute symptomatic infections. However, it is unclear to what extent asymptomatic infections were prevented by the vaccine and whether it is effective enough in patients at risk for a complicated course, such as patients with liver cirrhosis, immunosuppressed individuals and pregnant women. Efficient in vitro models are increasingly enabling the development of monoclonal neutralising antibodies for passive immunisation or therapy.Future vaccines should demonstrate clear protection against all genotypes in addition to a very good safety profile. The development of an efficient passive immunisation strategy, especially for immunosuppressed individuals, is desirable.