Motivations and experiences in controlled human infection trials vs. phase I clinical trials: a survey study

BACKGROUND: Controlled human infection (CHI) trials deliberately expose healthy participants to a pathogen. Although they share design features with phase I clinical trials, CHI trials may differ in participant burden and administrative burden. Literature on CHI participant motivations and trial experience compared to phase I participants is limited. METHODS: We conducted a survey comparing motivation, decision-making, and ethical views among CHI and phase I participants, using a previously validated questionnaire. Descriptive and comparative analyses assessed motivational drivers and ethical attitudes. RESULTS: In total, 70 CHI and 98 phase I participants were included. Distribution of motivation was different for CHI compared to phase I participants, with reimbursement being a less prominent motivator, and more altruistic factors reported. CHI participants experienced more severe symptoms and reported symptoms as an important factor in the decision to participate. Views on key ethical principles such as reimbursement and burden of participation were similar between participant groups. CONCLUSION: Overall, findings suggest CHI participants experienced more symptoms than phase I participants, but that CHI participation was a well-informed decision, with symptom burden taken into account. This informs future CHI trial design and warrants further research on symptoms and participant experience in CHI trials.