Ethical acceptability of human challenge trials: Consultation with the US public and with research personnel

Human challenge trials (HCTs) may accelerate the development of treatments and vaccines, and deliver novel insights into the course and consequences of infection. However, HCTs are contentious because they involve purposely exposing volunteers to infection. Consultation with the public and other stakeholders is essential for understanding how HCTs can be most ethically and acceptably pursued. Previous research has found public support for COVID-19 HCTs, but little research has considered public attitudes towards HCTs in principle and the various factors making a trial more or less acceptable. Empirical data on the attitudes of research personnel is also missing. We generated an online survey covering overarching support/opposition towards HCTs, as well as factors of importance for deciding whether or not an HCT is ethically acceptable. Our sample of the US public represents the responses of 1500 participants sampled via Prolific, poststratified to be representative of the general US adult population. We additionally collected a convenience sample of 33 research personnel engaged in phase III clinical trials for infectious diseases. Estimates for the US public suggest substantial support for using HCTs to develop new vaccines, new treatments, and knowledge about diseases, with similarly high support among research personnel. The most important factors in determining acceptability of an HCT were the risk to participants and their comprehension of this risk. The general public, in particular, appear relatively unconcerned about participants' motivations, and favor higher payment in accordance with risk. This study adds to a growing body of public consultation surrounding HCTs, demonstrating high levels of support for their use in principle-not just in relation to COVID-19. The importance attributed to various ethically-relevant factors can help in designing HCTs with high public acceptance.