Review Article

Hepatitis E—A Concise Review of Virology, Epidemiology, Clinical Presentation and Therapy

M. C. Donnelly; L. Scobie; C. L. Crossan; H. Dalton; P. C. Hayes; K. J. Simpson

Disclosures

Aliment Pharmacol Ther. 2017;46(2):126-141. 

In This Article

Prevention of HEV Infection

Genotype 1 and 2 Infection

HEV is becoming a real global public health problem, and a focus on prevention of infection must be considered. Globally, basic sanitation must remain the first line of defence against HEV infection. However, it is recognised that during outbreaks, basic sanitation and simple health interventions do not adequately prevent additional infections. Therefore, a vaccine against HEV is highly desirable, particularly for residents living in highly endemic areas and for those at high risk of developing complications, eg, the immunosuppressed. As all HEV genotypes belong to the same serotype, it is thought that one HEV vaccine should provide protection against all HEV genotypes. Due to difficulties in culturing HEV, it has not been feasible to produce enough virus for vaccine production for either live attenuated or inactivated vaccine against this virus.[143] Vaccine development therefore relies on preparation of recombinant HEV antigens or DNA. At least 11 experimental vaccines have been evaluated in nonhuman primates.[143] Two recombinant HEV vaccines (developed from genotype 1) have been shown to have short-term efficacy in humans.[144,145] A genotype I HEV recombinant protein (rHEV) vaccine had been trialled in volunteers from the Nepalese army, however, this vaccine has been removed from the development pipeline.[143,144]

The long-term efficacy of the licensed Xiamen Innovax Biotech anti-HEV vaccine (Hecolin) has recently been studied in adult patients in China.[145] Patients were randomly assigned to receive either three doses of the HEV vaccine, or a hepatitis B vaccine. In the HEV vaccine group, 0.3 cases per 10 000 person-years were identified, compared with 2.1 cases per 10 000 person-years in the hepatitis B vaccine (control) group, affording a vaccine efficacy of 86.6%. On follow-up, the HEV vaccine induced antibodies against HEV and provided protection against HEV for up to 4.5 years, and importantly, no safety concerns relating to the use of this vaccine were reported. Although there were some clinical issues relating to this study, for example, the potential for missed cases of HEV despite vaccination due to the lack of regular follow-up assessments, the promise of a safe and effective anti-HEV vaccine seems achievable in the near future. The WHO SAGE working group on Hepatitis E has identified and recognised the need for reviewing the existing data on the safety, efficacy and cost-effectiveness of the licensed hepatitis E vaccine and identifying the potential indications and uses for the hepatitis E vaccine in the context of other hepatitis E preventative strategies.[146]

Genotype 3 and 4 Infection

In the Western world, as transmission is predominantly via undercooked foodstuffs there must be education on adequate cooking to minimise risk of transmission via the food chain: for example, the risk of HEV transmission via foodstuffs is significantly reduced by cooking meat for 1 min at 70°C.[147] With regard to prevention of transmission via contaminated blood products, there is no evidence at present to support the need for HEV negative blood components for pregnant women. At present in England, and more recently in Scotland, NHS Blood and Transplant recommend that HEV negative blood should be used in patients who have undergone allogeneic stem cell transplant or solid organ transplant.[148] The UK Advisory Committee on the Safety of Blood, Tissues and Organs make a number of additional recommendations regarding the use of HEV-screened blood components— Table 4 .[149]

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