Experiences and motivations of participants in Streptococcus pyogenes human challenge trials

Introduction Human challenge trials (HCTs) involve infecting participants with a pathogen under controlled conditions. They play an integral role in Streptococcus pyogenes vaccine development, however recruiting participants can be challenging. We explored the experiences and motivations of participants in two S. pyogenes HCTs: CHIVAS-M75 and the CHIPS trial. Methods CHIVAS-M75 participants ( N = 25) were invited to complete an online survey retrospectively, 3–4 years after HCT participation. In the CHIPS trial, questionnaires were administered to participants at different time points during their stay at the trial facility ( N = 60). Descriptive statistical analyses were performed with an inductive, descriptive content analysis informed by the Theoretical Domains Framework of Behaviour Change. Results Forty-eight of the 74 participants (65%) reported their HCT experience was as, or better than, they expected. Key themes were around participants achieving a win-win sense from contributing to the research, a need to keep them physically and emotionally comfortable, and setting realistic expectations. Recommendations for optimising participants' experiences are presented. The recommendations concern acknowledging participants' motivations for taking part, ensuring they are fully-informed, maximising comfort, and facilitating continuous trial improvements through co-design. Conclusion There are opportunities to optimise information provided during the consent phase around what to expect for the inpatient stay, including the likely severity of illness. Participants appreciate being given context about their role in the greater research picture, which can give their participation more meaning. Creating a comfortable and social environment for inpatients reduces the burden of participation. Optimising these factors may enhance participant recruitment and retention in HCTs.