Human challenge trials: identifying and weighting risks and benefits

Abstract

Human challenge trials are characterized by the intentional infection of volunteers, in an environment in which risks are controlled and minimized, for the purpose of studying and analyzing diseases, as well as developing and testing medicines and vaccines, on a small number of participants who accept, in a free and informed way, to take part in the research. Although the practice has existed, with variations, for centuries, the Covid-19 pandemic has made the debate around the subject more evident, especially given the urgent need to develop vaccines. On the one hand, human challenge tests allow the understanding of the disease and the production of vaccines at a faster speed, generating benefits for public health and the community. On the other hand, they raise several ethical questions, mainly in relation to the intentional causing of harm to participants, which seems to violate the principles of beneficence and non-maleficence, in addition to referring to traumatic experiences. From this context, this paper seeks to present the premises for the ethical debate regarding human challenge trials. Using the bibliographic review method, through content analysis, this paper initially seeks to historically situate the practice, in connection with its recent applications. Furthermore, the main benefits and risks of using controlled human infection are presented and critically analyzed. In the end, the hypothesis is confirmed: human challenge studies can be carried out ethically, as long as they comply with strict regulatory standards, based on ethical-normative parameters.