Controlled human infection model (CHIM) studies involve the intentional exposure of healthy research volunteers to infectious agents. These studies contribute to knowledge about the cause or development of disease and to the advancement of vaccine research. But they also raise ethical questions about the kinds of risks that should be permissible and whether limits should be imposed on research risks in CHIM studies. Two possible risk thresholds have been considered for CHIM studies. The first suggests constraining ethically permissible risks according (...) to a minimal risk threshold and the second endorses a higher risk threshold that excludes irreversible or fatal infections. I argue that neither of these thresholds is persuasive and situate questions about risk thresholds in CHIM studies within a broader debate about permissible risks in research. I argue that risks in CHIM studies should be constrained according to limits on research risks that do not offer corresponding benefits in all studies rather than developing a unique risk threshold for CHIM studies. I then propose five recommendations for the ethical assessment of risk in CHIM studies. (shrink)

Some early phase clinical studies of candidate HIV cure and remission interventions appear to have adverse medical risk–benefit ratios for participants. Why, then, do people participate? And is it ethically permissible to allow them to participate? Recent work in decision theory sheds light on both of these questions, by casting doubt on the idea that rational individuals prefer choices that maximise expected utility, and therefore by casting doubt on the idea that researchers have an ethical obligation not to enrol participants (...) in studies with high risk–benefit ratios. This work supports the view that researchers should instead defer to the considered preferences of the participants themselves. This essay briefly explains this recent work, and then explores its application to these two questions in more detail. (shrink)

Healthy volunteers in biomedical research often face significant risks in studies that offer them no medical benefits. The U.S. federal research regulations and laws adopted by other countries place no limits on the risks that these participants face. In this essay, I argue that there should be some limits on the risks for biomedical research involving healthy volunteers. Limits on risk are necessary to protect human participants, institutions, and the scientific community from harm. With the exception of self-experimentation, limits on (...) research risks faced by healthy volunteers constitute a type of soft, impure paternalism because participants usually do not fully understand the risks they are taking. I consider some approaches to limiting research risks and propose that healthy volunteers in biomedical research should not be exposed to greater than a 1% chance of serious harm, such as death, permanent disability, or severe illness or injury. While this guideline would restrict research risks, the limits would not be so low that they would prevent investigators from conducting valuable research. They would, however, set a clear upper boundary for investigators and signal to the scientific community and the public that there are limits on the risks that healthy participants may face in research. This standard provides guidance for decisions made by oversight bodies, but it is not an absolute rule. Investigators can enroll healthy volunteers in studies involving a greater than 1% chance of serious harm if they show that the research addresses a compelling public health or social problem and that the risk of serious harm is only slightly more than 1%. The committee reviewing the research should use outside experts to assess these risks. (shrink)

Risk–benefit assessment is a routine requirement for research ethics committees that review and oversee biomedical research with human subjects. Nevertheless, it remains unclear how to weigh and balance risks to research participants against the social benefits that flow from generating biomedical knowledge. In this article, we address the question of whether there are any reasonable criteria for defining the limit of permissible risks to individuals who provide informed consent for research participation. We argue against any a priori limit to permissible (...) research risks. However, attention to the uncertainty of potential social benefit that can be derived from any particular study warrants caution in exposing prospective research participants to a substantial likelihood of serious harm. (shrink)

“[T]he Precautionary Principle still has neither a commonly accepted definition nor a set of criteria to guide its implementation. “There is”, Freestone … cogently observes, “a certain paradox in the widespread and rapid adoption of the Precautionary Principle”: While it is applauded as a “good thing”, no one is quite sure about what it really means or how it might be..

Purposeful infection of healthy volunteers with a microbial pathogen seems at odds with acceptable ethical standards, but is an important contemporary research avenue used to study infectious diseases and their treatments. Generally termed ‘controlled human infection studies’, this research is particularly useful for fast tracking the development of candidate vaccines and may provide unique insight into disease pathogenesis otherwise unavailable. However, scarce bioethical literature is currently available to assist researchers and research ethics committees in negotiating the distinct issues raised by (...) research involving purposefully infecting healthy volunteers. In this article, we present two separate challenge studies and highlight the ethical issues of human challenge studies as seen through a well-constructed framework. Beyond the same stringent ethical standards seen in other areas of medical research, we conclude that human challenge studies should also include: independent expert reviews, including systematic reviews; a publicly available rationale for the research; implementation of measures to protect the public from spread of infection beyond the research setting; and a new system for compensation for harm. We hope these additions may encourage safer and more ethical research practice and help to safeguard public confidence in this vital research alternative in years to come. (shrink)

One of the key ethical requirements for biomedical research is that it have an acceptable risk-benefit profile (Emanuel, Wendler, and Grady 2000). The International Conference of Harmonization guidelines mandate that clinical trials should be initiated and continued only if “the anticipated benefits justify the risks” (1996). Guidelines from the Council for International Organizations of Medical Sciences state that biomedical research is acceptable only if the “potential benefits and risks are reasonably balanced” (2002). U.S. federal regulations require that the “risks to (...) subjects” be “reasonable in relation to anticipated benefits, if any, to subjects and the importance of the knowledge” to be gained from the .. (shrink)