Researchers find hepatitis E vaccination is 84% effective in an epidemic

Hepatitis E, a viral infection transmitted through contaminated water, remains a major public health concern, particularly in regions with limited access to clean water and sanitation. Its impact is most severe in areas experiencing humanitarian crises, where overcrowding and inadequate resources exacerbate the risk.

The disease’s symptoms, including jaundice and acute liver damage, are especially dangerous for pregnant women, with mortality rates reaching as high as 50% in this group. In response to these challenges, a groundbreaking study conducted in South Sudan has provided new insights into the effectiveness of the Hecolin vaccine.

The Bentiu internally displaced persons (IDP) camp in South Sudan, home to over 100,000 people displaced by conflict, has long grappled with hepatitis E outbreaks. Poor sanitation and frequent flooding create ideal conditions for the virus’s spread.

Between 2015 and 2016, the camp reported over 3,000 hepatitis E cases. Another outbreak began in August 2021, prompting urgent action from the South Sudan Ministry of Health and Médecins Sans Frontières (MSF).

To address the outbreak, a mass vaccination campaign using the Hecolin vaccine was launched in 2022. This marked the first large-scale use of the vaccine in an outbreak setting. Hecolin, developed in China and licensed since 2011, had previously demonstrated high efficacy in clinical trials but had not been widely deployed in outbreak contexts.

Administered in three rounds between March and October 2022, the campaign targeted residents aged 16 to 40, including pregnant women. By the end of the campaign, over 90% of the target population had received at least one dose, with 73% and 58% completing two and three doses, respectively.

A collaborative study led by MSF and supported by international research teams, including the Geneva Centre for Emerging Viral Diseases, sought to evaluate the vaccine’s effectiveness in this unique setting.

Published in the journal, The Lancet Infectious Diseases, the study employed a case–control design to measure the protection provided by two doses of Hecolin against medically attended hepatitis E.

The researchers identified 201 individuals with suspected hepatitis E who met the eligibility criteria for the study. Of these, 21 were confirmed cases through laboratory tests. Each case was matched with six controls based on age, sex, pregnancy status, and neighborhood. Vaccination status was verified through self-reports and vaccination cards, ensuring accuracy.

The study also examined the potential biases in health-seeking behaviors, comparing vaccination rates among test-positive and test-negative cases. This secondary analysis helped refine the estimated vaccine effectiveness, ensuring robustness against confounding variables. These methods allowed researchers to corroborate their findings across multiple analytical approaches.

The findings revealed a two-dose vaccine effectiveness of 84%, after adjusting for potential confounders. This level of protection aligns with previous clinical trial data and underscores the vaccine’s potential to reduce hepatitis E incidence significantly in outbreak settings.

“Our study demonstrated that two doses of the Hecolin vaccine provide substantial protection against hepatitis E,” said Andrew Azman, an epidemiologist at the Geneva Centre. “This is particularly promising for regions where logistical challenges make the full three-dose regimen difficult to implement.”

One of the most striking outcomes was the vaccine’s efficacy in a camp environment where approximately 20% of residents frequently travel in and out. This mobility often complicates vaccination campaigns, but the high coverage rates achieved—over 90% of the target population receiving at least one dose—highlight the feasibility of large-scale immunization efforts even under challenging conditions.

These results played a pivotal role in informing updated World Health Organization (WHO) recommendations. By endorsing a two-dose schedule for outbreak response, the study provided a more flexible and accessible strategy for tackling hepatitis E in vulnerable populations.

Samples collected from suspected cases were sent to Geneva for advanced testing, including RNA extraction and whole-genome sequencing. These analyses not only confirmed the vaccine’s effectiveness but also provided valuable data on the virus’s transmission dynamics.

“The laboratory findings were crucial in understanding the virus and improving diagnostic tests,” noted Isabella Eckerle, director of the Geneva Centre for Emerging Viral Diseases. “This synergy between field operations and scientific research is vital for developing better outbreak responses.”

Whole-genome sequencing of select samples further illuminated the genetic diversity of the virus circulating in the camp. This data contributed to refining diagnostic tools and tailoring public health strategies to the specific outbreak context. Such insights are essential for anticipating and mitigating future hepatitis E outbreaks in similar settings.

In addition to confirming the vaccine’s effectiveness, the study’s results informed the establishment of a global hepatitis E vaccine stockpile by the WHO. This stockpile aims to provide rapid access to vaccines during emergencies, potentially saving thousands of lives in future outbreaks. The creation of this stockpile reflects a growing recognition of hepatitis E as a significant global health challenge.

The Bentiu study represents a pivotal step in the fight against hepatitis E, demonstrating that the Hecolin vaccine can be a practical and effective tool in outbreak settings. By showing that two doses are sufficient to confer significant protection, the research offers a more accessible vaccination strategy for vulnerable populations.

“Our findings have the potential to transform how we respond to hepatitis E outbreaks,” concluded Azman. “The establishment of a global vaccine stockpile is a testament to the impact of this work.”

This research also underscores the importance of integrating scientific expertise with on-the-ground humanitarian efforts. The collaboration between MSF, international researchers, and local health authorities exemplifies the power of multidisciplinary approaches in addressing complex public health crises.

As climate change and conflict continue to drive displacement and increase the risk of waterborne diseases, the lessons from Bentiu provide a blueprint for tackling hepatitis E in similar contexts worldwide. The integration of scientific research with humanitarian operations ensures that interventions are both evidence-based and contextually relevant.

Future studies could explore the long-term impact of reduced-dose schedules and their applicability to other vaccine-preventable diseases. Such research would expand the scope of this study’s findings, potentially benefiting millions in under-resourced settings.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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