The ONWARD project was endorsed by the PREZODE label in October 2026. Bringing together a network of 200 researchers worldwide from cross-disciplinary backgrounds, it aims to protect Europe’s health through interdisciplinary collaboration and innovative approaches to Hepatitis E prevention and control.
The European Food Safety Authority (efsa.europa.eu) ranks hepatitis E virus among the priority foodborne pathogens for which One Health surveillance and integrated prevention and control strategies are needed. ONWARD (CA24140)- short for One Health Network Against Zoonotic Hepatitis E Viruses- is a European research network supported by COST (European Cooperation in Science and Technology), within the EU Horizon Europe framework. Launched in 2025, ONWARD brings together close to 200 scientists from 39 countries worldwide. Its stated aim is “protecting Europe’s health through interdisciplinary collaboration and innovative approaches to Hepatitis E prevention and control”. A conversation with Professor Dr Antonio Rivero-Juarez, virologist at IMIBIC in Córdoba, Spain, and Chair of ONWARD, and Assoc. prof. Adriana Aniță, DMV and virologist at “Ion Ionescu de la Brad” Iasi University of Life Sciences, Romania, and co-leader of ONWARD’s Working Group on Dissemination, Communication and Awareness.
Why is hepatitis E so difficult to study, and what makes defining the scope of the problem a challenge in itself?
Professor Dr. Antonio Rivero-Juarez: Hepatitis E virus (HEV) was first recognized as a zoonotic pathogen in 1997. Although infection in animals is predominantly asymptomatic, HEV poses a significant public health concern, particularly in immunocompromised individuals, in whom it can lead to chronic hepatitis, progressive liver disease and, in some cases, fatal outcomes. The list of hosts is not exhaustive, as research continues. Domestic pigs are considered the main animal reservoir of HEV, while wild boars and deer represent important wildlife hosts at the interface between domestic and wild animal populations. Between animals, transmission occurs primarily through the faecal–oral route, including direct or indirect exposure to contaminated faeces
In Europe, locally acquired HEV infection is predominantly foodborne and is commonly associated with raw or undercooked pork, particularly liver products. Filter-feeding shellfish have also been identified as an established foodborne transmission vehicle, while contaminated water remains another recognized route of transmission.
The close genetic relatedness between HEV strains circulating in animals and those infecting humans provides strong evidence of zoonotic transmission. Estimates of HEV prevalence in European pigs vary with the age of the animals sampled and with what is measured: antibodies indicate previous exposure, whereas viral RNA indicates current infection.
Because the infection is predominantly subclinical in animals and usually silent in people, HEV is substantially underdiagnosed on both sides, as well as among the drivers. Similar to other food-associated pathogens, intensification of livestock production and international movement of animals and animal products create additional opportunities for spread.
Despite its public health significance, no vaccine is currently licensed for veterinary use in pigs, and no specific antiviral treatment has been universally established for HEV infection. A recombinant HEV vaccine, developed by Xiamen University in China, has been licensed for human use in China. However, it has not received WHO prequalification, and its availability and regulatory status remain geographically limited. Consequently, prevention continues to rely primarily on effective food safety measures, improved hygiene and biosecurity practices, and enhanced surveillance across the animal–human interface.
How do you organize the research network in ONWARD?
Assoc. Prof. Adriana Elena Aniță: We began by setting up five working groups (WG). The first three focus on scientific questions, while WG4 and WG5 support the work of all three. Together, their remit covers the full range of concerns involved in preventing hepatitis E transmission and outbreaks.
- WG 1 develops common approaches to HEV diagnosis and surveillance in humans, animals, food and the environment.
- WG 2 is patient-oriented. It spans prevention measures, including vaccines, through to clinical trials for the development of new antiviral compounds.
- WG 3 addresses prevention and control from a farm-to-fork perspective.
- WG 4 oversees dissemination and awareness-raising.
- WG 5 is dedicated to engagement with European and international stakeholders and to our policy impact strategy.
How do you collaborate with European stakeholders?
Professor Dr. Antonio Rivero-Juarez: One of ONWARD’s main objectives is to raise the profile of hepatitis E virus, improving detection at the human-animal interface, making diagnosis affordable and accessible. Through the work of our working groups, we collaborate with several major actors to that end. Among them are the European Centre for Disease Prevention and Control (ECDC) and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID). Our clinical working group has drafted three protocol templates: one for observational studies, one for vaccine trials and one for therapeutic trials. By using common definitions and outcomes, teams in different countries will be able to compare their findings.
Regarding prevention, which focuses on controlling HEV at the animal level (WG 3), we are developing a range of strategies in collaboration with the Federation of Veterinarians of Europe (FVE) and other relevant stakeholders, including policymakers and organizations involved in animal health. Raising awareness among stakeholders across the food production chain is a key priority, particularly because HEV infection in animals is largely asymptomatic and therefore difficult to detect through routine clinical observation. From a livestock production perspective, implementing preventive measures against a pathogen that generally has no discernible impact on animal health or productivity may offer limited immediate economic incentives for farmers. This highlights the need for evidence-based risk assessment and targeted prevention strategies that also account for the public health implications of HEV transmission. WG3 is developing Farm-Level Risk Management Guidelines for pig production. For each proposed measure, the guidelines will consider the evidence, the likely cost to the farmer, and the time needed to put it into practice. We would like to discuss the recommendations with EFSA and representatives of the sector. Working Groups 3 and 5 also collaborate with the International Organization for Standardization (ISO) to contribute to the development of guidelines for the assessment of pork products, supporting the harmonization of approaches to HEV risk evaluation and food safety.
How have you introduced ONWARD to the different communities working on hepatitis E?
Professor Dr. Antonio Rivero-Juarez. During our first year, we presented ONWARD to colleagues in infectious diseases and clinical microbiology at ESCMID Global in Munich. In hepatology, we presented the network at the annual meeting of the Asian Pacific Association for the Study of the Liver in Istanbul. At the World Hepatitis Summit in Bangkok, Dr. İmran Hasanoğlu gave an invited talk on what a One Health approach can contribute to hepatitis E prevention. On the veterinary and food safety side, we presented ONWARD at the 8th International Conference of the European College of Veterinary Microbiology in Surrey, UK. At the International Association for Food Protection Annual Meeting in New Orleans, Nigel Cook introduced the network through a talk and a poster and discussed HEV surveillance data with food virologists. These audiences came together at the 9th World One Health Congress in Lisbon, where we presented a poster introducing ONWARD. For readers interested in how the network works, the poster is a good place to start: it gives an overview of how colleagues working in human health, veterinary medicine and food safety are tackling hepatitis E together.
How do you support young researchers’ work?
Assoc. prof. Adriana Elena Aniță: We support early-career researchers in several ways. Our conference grants help them present their own findings at international meetings, and our short-term scientific missions allow them to spend time in a partner laboratory, learn a method and apply it to a research question with the host team. We also offer practical training.
In September 2026, 25 trainees came to Córdoba, Spain, for our first Training School on rat hepatitis E virus (ratHEV), where they worked on serological testing, molecular detection and sequencing.
We also want young researchers to help shape the future research priorities of the network. That is the idea behind the first ONWARD Assemble, which will take place in Bucharest on April 20-22, 2027. We expect to welcome more than 100 participants, with travel support prioritized for approximately 80 young researchers and innovators. The programme will provide a dedicated space for participants to present their research ideas to colleagues from different disciplines, explore opportunities for collaboration, build new partnerships and develop joint initiatives to take their ideas forward.
What made you apply to the PREZODE labelling scheme?
Professor Dr. Antonio Rivero-Juarez: PREZODE provides ONWARD with an international framework in which hepatitis E can serve as a concrete model for the prevention of zoonotic emergence. ONWARD is developing harmonized diagnostic and sequencing protocols, integrated surveillance recommendations, farm-level risk-management guidelines, protocols for hunting and environmental settings, food-chain risk assessments and guidance for human populations at increased risk. These outputs cover the complete pathway from detecting the virus to reducing exposure and translating evidence into policy. We would like to work with PREZODE in several practical areas. First, HEV and ratHEV could be used as a disease-specific case study for integrated surveillance across humans, animals, food and the environment. Second, PREZODE’s regional and international network could help us adapt ONWARD protocols and training activities to settings outside Europe, particularly in African countries where diagnostic and surveillance capacity remains uneven. Third, we could jointly organize stakeholder consultations and prepare policy briefs on farm-level prevention, food safety, early detection and the integration of HEV into One Health surveillance systems.
Assoc. prof. Adriana Elena Aniță: ONWARD could contribute the technical and disease-specific expertise, while PREZODE could connect these results with a wider community of institutions, regional networks and decision-makers. A first practical step could be to identify one joint activity for 2027, such as a workshop, webinar or HEV demonstrator project, and to involve PREZODE representatives in the ONWARD Assemble and stakeholder workshops.
What collaboration between ONWARD and PREZODE are you looking forward to in practice?
Professor Dr. Antonio Rivero-Juarez: We see hepatitis E and rat hepatitis E as two useful starting points for collaboration. For hepatitis E, one question is whether findings in pigs and pork products reach the teams investigating human infections, and whether those teams can use that information to guide prevention. Rat hepatitis E raises a different question: if laboratories do not routinely test for it, what does the absence of reported human cases actually tell us? Working with PREZODE will allow us to explore these questions with partners whose surveillance systems and public health priorities differ from those in Europe. One practical starting point is ONWARD’s survey of diagnostic capacity. We could share the questions and findings with interested PREZODE partners, particularly in Africa, and ask which gaps they recognize in their own settings and which ones our survey may have overlooked. Those discussions could guide joint trainings, drawing on our experience in Córdoba, and help us agree on a few useful indicators. For example, knowing which laboratories can investigate suspected ratHEV infection, and where clinicians can refer samples, would give us a better basis for interpreting differences in case reporting between countries. There is also scope to work together on prevention. As ONWARD develops its assessment of HEV risk in pigs before slaughter, PREZODE could help bring producers, veterinarians, food safety authorities and public health teams into the discussion. Its contribution would be particularly useful before recommendations are finalized: which measures are feasible on farms, who would be responsible for implementing them, and what evidence would an authority need to recommend them? A joint workshop on one of these questions could provide the basis for a short policy brief addressed to the people in a position to act on it.
Assoc. prof. Adriana Elena Aniță: The 2027 ONWARD Assemble in Bucharest offers an excellent opportunity to bring PREZODE partners together with ONWARD working groups and early-career researchers. We hope these discussions will help identify one or two concrete collaborative activities that both networks are keen to pursue, such as a joint training initiative, an exchange of experience on surveillance practices, or the development of a joint funding proposal. This would provide a clear starting point for the collaboration while giving early-career researchers an active role in shaping its future direction.
Another question we would like to explore together with PREZODE is what practical measures could encourage and support farms in adopting effective strategies to prevent hepatitis E virus (HEV) transmission. As ONWARD prepares its assessment of HEV risk in pig production, PREZODE could help us bring worldwide stakeholders into the discussion while there is still time for their experience to shape the recommendations. We would like to hear which measures they consider feasible, what they would need to put them into practice, and where advice developed for European farms would need to be adapted. In return, ONWARD offers E a concrete case for its work on preventing zoonotic infections at source: how do you make prevention worthwhile for farmers when the infection usually goes unnoticed in pigs, and the main health benefit is to people?