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Inno4Vac publication outlines the future of ethical and regulatory oversight for human challenge studies in vaccine development

  • Jul 3
  • 2 min read

The Inno4Vac Consortium announces the publication of a comprehensive report outlining key ethical and regulatory considerations for the future use of Controlled Human Infection Models (CHIMs) in vaccine and therapeutic research.

June 2026


Published in Biologicals, the report summarises discussions and recommendations from the fourth Inno4Vac stakeholder workshop, "Refining the Regulatory and Ethics Context of Controlled Human Infection Models", held on 17 October 2025 in Leiden, The Netherlands. The workshop brought together researchers, regulators, ethicists, industry representatives, and clinical experts to address emerging challenges associated with the growing use of CHIMs in infectious disease research.


CHIMs involve the controlled exposure of healthy adult volunteers to carefully characterised pathogens under highly monitored conditions. These models have become increasingly important for understanding infection mechanisms, identifying immune correlates of protection, and accelerating the evaluation of vaccines and therapeutics.

A central focus of the workshop was the evolving ethical and regulatory landscape surrounding CHIMs. Participants identified several areas requiring further attention, including:

  • Regulatory classification of challenge agents under European clinical trial frameworks;

  • Management and assessment of risks to third parties ("bystander risks");

  • Ethical considerations surrounding outpatient versus inpatient challenge studies;

  • Harmonisation of manufacturing and quality requirements for challenge agents;

  • Improved communication and collaboration between researchers, ethics committees, and regulators;

  • Enhanced community and participant engagement throughout CHIM development.


The report also presents case studies from Inno4Vac's ongoing efforts to develop challenge models for toxigenic Clostridioides difficile, RSV-B, and influenza A(H3N2) aiming to complement the toolbox of predictive and clinically relevant CHIMs for evaluating future vaccines and therapies.


“CHIMs have become an essential research strategy for accelerating the development and evaluation of vaccines and therapeutics across a range of infectious diseases. However, their successful implementation depends on continuous dialogue between researchers, regulators, ethics committees, industry, and society to ensure they remain safe, ethical, and scientifically robust." – Nicola Viebig, European Vaccine Initiative Director of Research.

The workshop discussions underscored the importance of appropriate ethical oversight that reflects both the available evidence and the level of uncertainty associated with individual CHIM studies.


Sustained Stakeholder engagement and adaptive regulatory approaches will be essential for realizing the full potential of CHIMs to support the development of safe, effective, and accessible vaccines worldwide.





This project has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 101007799 (Inno4Vac). This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and EFPIA (www.imi.europa.eu). This communication reflects the author´s view and neither IMI nor the European Union, EFPIA, or any Associated Partners are responsible for any use that may be made of the information contained herein

 
 
 

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