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Payment in challenge studies: ethics, attitudes and a new payment for risk model
  1. Olivia Grimwade1,2,
  2. Julian Savulescu2,3,4,
  3. Alberto Giubilini2,5,
  4. Justin Oakley6,
  5. Joshua Osowicki7,8,
  6. Andrew J Pollard9,
  7. Anne-Marie Nussberger10
  1. 1 Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
  2. 2 Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
  3. 3 Murdoch Childrens Research Institute, Parkville, Victoria, Australia
  4. 4 Melbourne Law School, University of Melbourne, Melbourne, Victoria, Australia
  5. 5 Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
  6. 6 Monash Bioethics Centre, Monash University, Melbourne, Victoria, Australia
  7. 7 Tropical Diseases Research Group, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
  8. 8 Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
  9. 9 Department of Paediatrics, University of Oxford, Oxford, UK
  10. 10 Department of Experimental Psychology, University of Oxford, Oxford, UK
  1. Correspondence to Professor Julian Savulescu, Faculty of Philosophy, University of Oxford Uehiro Centre for Practical Ethics, Oxford, Oxfordshire, UK; julian.savulescu{at}


Controlled Human Infection Model (CHIM) research involves the infection of otherwise healthy participants with disease often for the sake of vaccine development. The COVID-19 pandemic has emphasised the urgency of enhancing CHIM research capability and the importance of having clear ethical guidance for their conduct. The payment of CHIM participants is a controversial issue involving stakeholders across ethics, medicine and policymaking with allegations circulating suggesting exploitation, coercion and other violations of ethical principles. There are multiple approaches to payment: reimbursement, wage payment and unlimited payment. We introduce a new Payment for Risk Model, which involves paying for time, pain and inconvenience and for risk associated with participation. We give philosophical arguments based on utility, fairness and avoidance of exploitation to support this. We also examine a cross-section of the UK public and CHIM experts. We found that CHIM participants are currently paid variable amounts. A representative sample of the UK public believes CHIM participants should be paid approximately triple the UK minimum wage and should be paid for the risk they endure throughout participation. CHIM experts believe CHIM participants should be paid more than double the UK minimum wage but are divided on the payment for risk. The Payment for Risk Model allows risk and pain to be accounted for in payment and could be used to determine ethically justifiable payment for CHIM participants.

Although many research guidelines warn against paying large amounts or paying for risk, our empirical findings provide empirical support to the growing number of ethical arguments challenging this status quo. We close by suggesting two ways (value of statistical life or consistency with risk in other employment) by which payment for risk could be calculated.

  • research ethics
  • coercion

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  • Contributors OG, JS, AG and A-MN contributed to the study design, drafting and editing of the manuscript. AJP, JuO and JoO provided feedback on the study design and the manuscript. OG and A-MN performed the analysis of the data. OG wrote the first draft of the paper. All authors authorised the final version of the manuscript.

  • Funding JS and AG were supported by the Wellcome Trust (203132/Z/16/Z and 104848/Z/14/Z). JS, AJP and AG are members of the Oxford Martin Programme for Collective Responsibility for Infectious Disease. JS through his involvement with the Murdoch Children’s Research Institute was supported by the Victorian Government's Operational Infrastructure Support Program. AG was supported by an AHRC/UKRI grant (AH/V006819/1).

  • Disclaimer The views expressed in this article do not necessarily represent the views of Department Health and Social Care (DHSC), Joint Committee on Vaccination & Immunisation (JCVI), National Institute for Health Research (NIHR) or WHO.

  • Competing interests AJP and JoO are both Controlled Human Infection Model (CHIM) investigators. JoO is an investigator on CHIM studies funded by the Australian National Health and Medical Research Council & Medical Research Future Fund. AJP is a CHIM investigator and codirector of the UK MRC Hic-Vac network. AJP is Chair of UK DHSC's JCVI and is a member of the WHO’s SAGE. AJP is an NIHR Senior Investigator.

  • Patient consent for publication Not required.

  • Ethics approval The University of Oxford Social Sciences & Humanities Interdivisional Research Ethics Committee granted ethics approval for this project.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data and code are available upon request.

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