Hepatitis E

Hepatitis is an inflammation of the liver, most commonly caused by viral infection. There are five primary types of infectious hepatitis: A, B, C, D, and E.

Hepatitis E is a liver disease caused by the hepatitis E virus (HEV), primarily transmitted through contaminated water and food. There are an estimated 20 million infections every year, though the true burden and epidemiology of the disease is understudied and poorly understood. There are four genotypes, each with a distinct route of transmission. Types 1 and 2 are transmitted through the oral-fecal route. This means people who are infected with HEV shed the virus in their stool, which can contaminate sources of drinking water. HEV 1 and 2 are prevalent worldwide and particularly in East and South Asia and sub-Saharan Africa, especially in places with limited access to water, sanitation, and hygiene services. Types 3 and 4 are zoonotic, meaning they can be transmitted from animals to humans, often through contaminated animal meat products. These types are not as common but also found worldwide.

HEV 1 and 2 can be particularly severe and potentially fatal for high-risk groups, including people who are pregnant, immunosuppressed, and those with pre-existing chronic liver disease. Although a highly efficacious vaccine, Hecolin®, is registered in China and Pakistan, the vaccine has rarely been used in global health settings.

Advancing hepatitis E control

The International Vaccine Institute is at work to understand the burden of HEV disease and to evaluate the available vaccine in at-risk populations to generate evidence to inform policy for use of vaccine and disease control:

Understanding the burden of hepatitis E
  • National serosurvey in Nepal, a country with burden of hepatitis E, to better understand the true burden of disease and the risk factors.
  • Retrospective serostudies with three partner institutions in the Democratic Republic of the Congo, Nigeria, and Senegal to fill critical data gaps and generate hepatitis E disease burden estimates in sub-Saharan Africa. From 2020-2022, the Hepatitis E Epidemiology in Africa project generated comprehensive HEV disease burden data spanning 10 years and 13 countries in Central and Western Africa.
  • In Burkina Faso, IVI is leading a facility-based observational prospective cohort study to evaluate the impact of hepatitis E on pregnancy outcomes and maternal health. The primary objective is to assess the incidence of early neonatal mortality in women who do or do not have HEV infection.
  • In Sri Lanka, the Rajarata Pregnancy Cohort Infectious Disease project assesses how exposure to leptospirosis and/or HEV before or during pregnancy impacts pregnancy outcomes for both mothers and their babies. The project is investigating whether exposure to leptospirosis and HEV is associated with adverse pregnancy outcomes. Secondly, the project is looking at the level of exposure of pregnant women to these diseases in semi-urban settings in Sri Lanka.
Generate evidence to inform policy for use of vaccine in high-risk populations
  • Conducting a Phase II trial of Hecolin® in Pakistan to establish safety and immunogenicity of the vaccine in pregnant women.
  • Conducting a Phase II trial of Hecolin® to establish safety and immunogenicity of the vaccine in children 2-15 years and in adults living with HIV in South Africa.

Page updated: March 2025