• research ethics
• clinical trials
• ethics
• public health ethics

Human infection challenge studies (HCSs) provide illuminating case studies for several ongoing debates in research ethics, including those related to research risks and payment of participants. Grimwade et al 1 add to previous public engagement, qualitative evidence and philosophical literature on these topics.1–8 The authors advocate revision of research payment policy and practice based on their main finding that members of the public endorse ex ante payment of participants proportional to research-related risk exposure, in addition to post hoc compensation for any lasting harms that occur.1

Although ‘payment for risk’ would diverge from most current research ethics guidelines, it is noteworthy that the difference in payment to participants that their framework would allow might only be small, at least in the case of currently accepted studies. The absolute difference would likely be small because the risk of currently accepted HCS participation (after risk minimisation strategies) is usually very low.9 10 On a ‘value of statistical life’ approach, mirroring actuarial accounting for fatal risks, a 1 in 100 000 risk of death might attract an extra payment of only US$96.1 Most HCS do not involve fatality risks this high, although, on pessimistic estimates, the risk of COVID-19 HCS in young healthy adults might involve similar levels of risk.11 Such risks might arguably be justified by large expected public health benefits,12 ,9 11 13 but it remains controversial whether higher levels of payment could …