RT Journal Article SR Electronic T1 Payment in challenge studies: ethics, attitudes and a new payment for risk model JF Journal of Medical Ethics JO J Med Ethics FD BMJ Publishing Group Ltd and Institute of Medical Ethics SP 815 OP 826 DO 10.1136/medethics-2020-106438 VO 46 IS 12 A1 Grimwade, Olivia A1 Savulescu, Julian A1 Giubilini, Alberto A1 Oakley, Justin A1 Osowicki, Joshua A1 Pollard, Andrew J A1 Nussberger, Anne-Marie YR 2020 UL http://jme.bmj.com/content/46/12/815.abstract AB 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.