World Hepatitis Day is a global health campaign hosted by the World Health Organization dedicated to raising awareness of hepatitis and encouraging greater response from individuals, partners, and the public. The campaign date July 28 pays homage to Dr. Baruch Blumberg, celebrating the birthday of the Nobel Prize-winning scientist who discovered hepatitis B.

Hepatitis is an inflammation of the liver, which is most commonly caused by viral infection. It can also be a result of liver damage caused by toxic substances or, even more rarely, by autoimmune disease. It can be self-limiting and acute, but chronic hepatitis may cause scarring of the liver, loss of liver function, or liver cancer. Acute infection may yield limited or no symptoms, but they can include muscle/joint pain, abdominal pain, nausea, dark urine, itchy skin, and jaundice. There are five primary types of infectious hepatitis: A, B, C, D, and E.

• Hepatitis A is primarily transmitted through the ingestion of infected food and water, causing an acute, short-term illness. Hepatitis A is preventable with vaccination.
• Hepatitis B (HBV) is transmitted through exposure to infected bodily fluids, such as blood, semen, and saliva. It can lead to both acute and chronic disease, often resulting in liver cirrhosis or cancer. A highly effective vaccine is also available to prevent HBV.
• Hepatitis C also spreads mostly through exposure to infected bodily fluids. Chronic infection can lead to severe liver damage. While effective treatments are available, there is not yet a vaccine for hepatitis C.
• Hepatitis D only occurs in those already infected with HBV. It is transmitted through blood and other bodily fluids, and it can worsen the severity of HBV infections.
• Hepatitis E (HEV) is primarily transmitted through consumption of infected food and water. It often causes acute outbreaks, especially in developing countries. While there is a licensed vaccine, it is not yet widely available.

Hepatitis E (HEV) is the leading cause of acute viral hepatitis, with an estimated 20 million infections annually. There are four genotypes of the virus with different routes of transmission. Types 1 and 2 are transmitted through the oral-fecal route. This means that people who are infected with HEV shed the virus in their stool, which can contaminate sources of drinking water. HEV 1 and 2 are found worldwide, but most cases are concentrated in low- and middle-income countries across East and South Asia and sub-Saharan Africa, where there is limited access to water, sanitation, and hygiene (WASH) services and infrastructure. Types 3 and 4 are zoonotic, meaning they are spread from animals or animal meat products to humans through an oral route, such as eating inadequately cured meats. These types are less common but also have a wide geographic distribution, including in high-income countries where they are known to cause severe disease in immunocompromised individuals.

HEV 1 and 2 can be a particularly severe and potentially fatal infection for high-risk groups, such as women in their second or third trimester of pregnancy. Pregnant women have been found to be at greater risk of HEV-induced liver failure, and the risk of death soars to 25-30% if they contract HEV in their third trimester. Pregnant women and people living in settings with insufficient WASH services are therefore priority groups for vaccination efforts. While there is one highly efficacious vaccine, Hecolin®, it is only registered for domestic use in China and Pakistan, limiting its widespread implementation.

In line with a mandate to accelerate vaccines for poverty-associated infectious diseases, IVI has been driving pivotal implementation research to make Hecolin® vaccine more available. In 2024, IVI launched a Phase II clinical trial in Pakistan to evaluate the safety and immunogenicity of Hecolin® in both pregnant and non-pregnant women. This study, conducted under the supervision of Aga Khan University, aims to enroll over 2,300 participants across four sites in Karachi. The goal is to further generate essential safety and immunogenicity data in pregnant women to facilitate use of the vaccine in a group at highest risk for severe HEV and related complications. The team, led by Dr. Julia Lynch, Program Director at IVI, aims to advance recommendations for use of this vaccine and steps toward WHO prequalification, which would enable the vaccine’s global use and accessibility.

Dr. Lynch shares, “Although there is a safe and highly effective hepatitis E vaccine evaluated among healthy adults in China, the available data on the product is insufficient to support broader use. That’s what we’re trying to change by generating more information on the vaccine’s safety and immunogenicity in high-risk groups including pregnant women and immunosuppressed people, and in children. We hope to provide data to inform policy makers and support prequalification of the vaccine which will greatly expand accessibility.”

With additional funding from the Bill & Melinda Gates Foundation and Open Philanthropy, IVI is conducting a separate study to evaluate the vaccine’s safety and immune response in HIV-positive and negative adults, and in healthy children in South Africa. To further expand policy recommendations for the use of Hecolin® vaccine, the results of this study will generate necessary evidence to support the inclusion of children and people living with HIV/AIDS at risk of HEV infection in vaccination efforts.

In addition to vaccine clinical development, IVI is involved in epidemiological studies to fill gaps in hepatitis E disease burden data. Initiated in 2021, IVI’s Hepatitis E Epidemiology in Africa (HEVA) project collaborates with researchers from the Democratic Republic of the Congo, Nigeria, and Senegal to generate disease burden estimates and gain a more accurate picture of hepatitis E prevalence across sub-Saharan Africa. By 2022, the project completed serologic screenings of nearly 14,000 samples and continued analyzing seroepidemiology, spatial distributions, and seasonality data into the next year, which are crucial for understanding the disease’s spread and impact in these regions.

As one of the most devastating and neglected diseases, it is essential that the global health and wider international community raise awareness, advocate, and make meaningful progress toward HEV prevention and elimination. Through vaccine clinical research and development, public-private collaboration, and advocacy, IVI is working to drive innovations to reduce the burden of hepatitis and ensure a healthier future for all.

by Wendy Li

Last updated July 28, 2024