Our Clinical Research 101 series takes an in-depth look at key steps and tips for navigating the clinical research process. The fifteenth installment in our Clinical Research 101 series is by CHÉOS Scientist Dr. Anita Ho.

*This post was originally published in 2019 and was updated in 2022.

In addition to being a Scientist at CHÉOS, Anita is currently a Clinical Associate Professor in bioethics and health services research at the Centre for Applied Ethics at the University of British Columbia, and an Associate Adjunct Professor in the Bioethics Program at the University of California, San Francisco. She is the former Director of Ethics Services at Providence Health Care. If you would like to inquire about our services, please submit your request here.

What is vulnerability?

According to the Tri-Council Policy Statement 2 (TCPS2), which guides the ethical conduct of research involving humans and/or human biological materials in Canada, vulnerability refers to a diminished ability to fully safeguard one’s own interests in the context of a research project. This vulnerability may be caused by a number of factors, including limited decision-making capacity.

Vulnerability is not an inherent quality of an individual or group, but describes the situation or circumstances that may make a person vulnerable in the context of a specific research project or setting. As stated by the TCPS2, people should not automatically be considered vulnerable because of assumptions made about the group to which they belong. A person’s particular circumstances should be considered in the context of the proposed research project.

If a group of people is experiencing vulnerability in a particular situation, setting, system, or society, that vulnerability is a result of other people or structural barriers. However, if left undefined, readers or listeners may make assumptions about vulnerability being inherent to a specific individual, group, or community. Therefore, it is important to clearly articulate what it is we mean by vulnerability in each context.

Understanding power dynamics in research

Limited decision-making capacity may be especially important in the context of clinical research because knowledge and power asymmetry may exist between researchers and participants. This power imbalance means that decisional limitations may exacerbate certain people’s susceptibility to coercion, manipulation, or exploitation. Participants experiencing vulnerability may include children, institutionalized persons, and others whose diminished competence or decisional capacity can render them incapable of adequately understanding what it means to participate in research, their rights as a research participant, and the implications (e.g., risks and benefits) of enrolling in a research study.

People may also experience vulnerability because they have been subjected to various forms of structural inequalities or have limited rights, opportunities, and power. These disadvantages may mean people are less able to advocate or care for themselves in ways they see fit. Some examples may include people of Indigenous backgrounds and minority ethnic groups, people who are socio-economically disadvantaged, and people with stigmatized conditions, such as various mental illnesses, substance use disorders, or infectious diseases.

It should be noted that the determination of any population group as being potentially vulnerable is dynamic, relative, and often imperfect, because the nature of those groupings is culturally dependent and may also be related to the particular research project. Moreover, people may experience different degrees of vulnerability and at different times, depending on their particular circumstances.

Ethical Considerations

Vulnerability is most often discussed in relation to the concept of informed consent but is also related to other important research ethics principles and practices. As respect for personal autonomy, prevention of harm, and promotion of justice are widely accepted ethical principles of responsible research, the possibility that some communities and individuals may be susceptible to exploitation or harm due to their vulnerable circumstances raises important ethical concerns.

The TCPS2 emphasizes the principle of Respect for Persons. Recognizing researchers’ broad ethical obligation to uphold respect for all persons and to promote fairness and equity, this principle highlights the duty of researchers to determine if their research may require special procedures to ensure that participants are not rendered vulnerable due to the research, and that they are protected against abuse, exploitation, discrimination, and undue harm. For example, researchers may consider if having additional channels and opportunities for research participants to gather more information regarding the research project, voice their concerns, or withdraw their participation or data sharing consent may help to enhance all prospective participants’ autonomy and interests.

Attention to vulnerability is also important from the ethical perspective of fair distribution of benefits and burdens. For example, in global pharmaceutical research, there are often concerns about whether people from resource-poor regions, who may be heavily recruited by researchers for vaccine or intervention trials, would be able to afford the expensive treatments developed based partly on their contribution. Recruitment of participants who face economic vulnerability and may be denied the benefits of the knowledge generated but are subjected to a larger share of research risks (e.g., side effects of an experimental treatment) may exacerbate their undue burdens and ongoing health inequity.

Protection of people who may be rendered vulnerable: A note of caution

While protection of participants from exploitation and other undue influences is important in promoting respect, as research professionals we need to ensure that individuals, groups, and communities whose situation or circumstances may render them vulnerable are not unfairly excluded from research opportunities. Over-protectionist attitudes or practices by researchers or Research Ethics Boards (REBs) may ironically reinforce people’s vulnerable circumstances. The inclusion of people of different demographic and socio-economic backgrounds in research is also scientifically important, as it helps to ensure that treatments frequently given to these populations are effective and safe.

To fully respect the autonomy and well-being of people who may otherwise be in vulnerable circumstances and to promote justice and fairness in research, engagement with community stakeholders is vital. Consultation and collaboration with relevant stakeholders can help to determine the most appropriate ethical framework and procedures for research participation and benefit sharing that are fitting for people’s contexts and realities. For example, the TCPS2 recommends that, when a research project is likely to affect the welfare of an Indigenous community or its members, researchers should engage with that community.

References and Further Reading

Government of Canada: Panel on Research Ethics. Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans – TCPS 2. www.pre.ethics.gc.ca. Data modified: 2017 Nov 12.
Benatar SR. Avoiding exploitation in clinical research. Cambridge Q Healthcare Ethics. 2000 Oct;9(4):562-5.
Stranges J. Words matter: The use of ‘vulnerable’ in health care and public health. UnityHealth.to. 2019 Aug 30.
Bracken-Roche D, Bell E, Macdonald ME, et al. The concept of ‘vulnerability’ in research ethics: an in-depth analysis of policies and guidelines. Health Res Policy Syst. 2017 Feb 7;15(1):8.
Denny CC, Grady C. Clinical research with economically disadvantaged populations. J Med Ethics. 2007 Jul;33(7):382-5.
Luna F. Elucidating the concept of vulnerability: Layers not labels. Int J Feminist Approach Bioethics. 2009;2(1):121-39.
Macklin R. Bioethics, vulnerability, and protection. Bioethics. 2003 Oct;17(5-6):472-86.
Rogers W, Ballantyne A. Special populations: Vulnerability and protection. RECIIS. 2008;5(4):11-38.