Background
Research involving human participants plays an important role in advancing knowledge, but also requires thoughtful ethical, legal, and practical consideration to ensure engagement is fair, safe and respectful.
While some studies are designed from the outset to recruit participants who are already recognised as vulnerable, and therefore include the necessary safeguards, inclusive research requires a broader approach. When research aims to involve a sample that reflects the general population, it is useful to move beyond fixed categories of vulnerability (such as children, people in care environments, or those in custodial settings). Instead, a contextual approach helps identify situations in which any participant may be vulnerable – either at the recruitment stage or because of the nature or topic of the research itself.
This guidance outlines key considerations around recruitment, consent, and safeguarding. It also signposts to relevant policies and legislation to support responsible practices and help researchers identify when participants may require additional protections.
Who Are Vulnerable Participants?
Vulnerability can be defined in different ways. In research, vulnerable participants are defined as individuals who may be at a higher risk of experiencing coercion or undue influence, including people who might not fully understand what it means to participate, or who may have difficulty providing informed consent (Brule & Eckstein, 2017).
People may be vulnerable due to:
- Age
- Marginalisation
- Disability
- Imbalances of power
- Prior experiences
- Susceptibility to physical or psychological harm
- Limited (or no) freedom or capacity to consent
Different groups may be considered vulnerable in different situations. ‘Vulnerability’ is therefore a dynamic concept and must be considered on a case-by-case basis. Many groups or individuals not otherwise considered vulnerable could be exposed to issues that make them vulnerable as a result of participating in research (UK Research and Innovation, 2023). For example, participants who have experienced a traumatic life event may be particularly vulnerable when asked to discuss it. Additionally, certain topics may cause distress, potentially making people vulnerable due to the sensitive nature of the content.
Informed Consent
Every effort should be made to obtain freely given, informed consent from the participant themselves. Although vulnerabilities may introduce barriers to understanding or decision-making, researchers need to put appropriate measures in place to support participants in providing fully informed consent.
Potential participants must be clearly informed about any risks that go beyond those encountered in everyday life, including risks that may be heightened by their vulnerability. For example, research involving sensitive or distressing topics may have a greater emotional impact on some individuals. Participants need to be given clear, accessible information about the nature of the research, what participation involves, and any potential impacts, so that they can make an informed decision.
Mental Capacity
Some people may not have the capacity (legal and/or mental) to provide informed consent to take part in research. Capacity in this context refers to the ability to understand what the research involves, in order to make an informed decision about taking part.
The Mental Capacity Act 2005 applies to everyone in England and Wales who is involved in supporting adults aged 16 and over who are unable to make some or all decisions for themselves. It provides a legal framework for decision-making for those who lack the mental capacity to make decisions due to illness or disability.
When working with certain vulnerable groups, researchers must consider that some participants may not have the capacity to provide consent.
Researchers also need to also be aware that a person’s capacity may be permanent or temporary. In some cases it may fluctuate over time. For instance, some individuals with Dementia may have fluctuating capacity, where their ability to understand and make decisions can change during any given time period.
Where Mental Capacity Assessments are required, researchers must note that specific training is required to undertake these, and therefore additional procedures or interaction with gatekeepers/professionals may be required in the study protocol.
Research projects involving individuals who lack capacity must be reviewed by an NHS REC. More information can be found on the Health Research Authority webpages and guidance on obtaining Sponsorship from the University of Bath can be found here. If you have queries about the NHS REC or Sponsorship processes, please contact us via nhs-sponsorship@bath.ac.uk.
Children and Young People
For research involving children, there are specific requirements to consider when obtaining informed consent. In this guidance, we make the distinction between children under 16 years of age, as well as young people aged 16 to 18. Whilst additional considerations are needed, it is important to remember that children are capable members of society whose voices have a right to be heard.
For children under 16, parental consent is typically a requirement. Parents/Guardians should be fully informed about what their child's participation would involve and be asked to provide informed consent. To respect their autonomy, children should also provide their assent in a manner appropriate to their age and understanding, having received age-appropriate information. If a child expresses dissent, verbally or non-verbally, it must be respected, even if parental consent has been given. Parents/guardians also retain the right to withdraw consent at any time.
There are limited circumstances where obtaining parental consent may not be appropriate, and a child under 16 may be able to provide consent themselves (known as Gillick competence).
For example, there may be situations where parental involvement could negatively impact the child’s wellbeing or compromise their autonomy. These situations require careful ethical consideration and researchers must seek guidance from research-ethics@bath.ac.uk before proceeding. Importantly, parental consent must not be bypassed for reasons of convenience or logistical ease. More detailed guidance on Gillick competence is in development.
Young people aged 16 to 18 are generally considered capable of providing consent for themselves. Whilst parental consent is not a legal requirement for this age group, it is considered good practice to also obtain parental consent where appropriate and feasible in the research context. Remember that consent is an ongoing process. Children who are initially recruited at age 15 or younger, but turn 16 during the study, will need to be re-consented by providing their own consent.
Remember, researchers should consider how age ranges for children and young people may be defined across different contexts. Experiences of children and young people can vary diversely, and you should ensure this is reflected appropriately in your own research project. Consider how participatory approaches could be utilised by involving children and young people as active partners in your research.
Guidelines for obtaining consent from children and young people may differ depending on the location of the research and the nature of the study. For instance, Clinical Trials of an Investigational Medicinal Product (CTIMPs) follow specific regulations, and Scotland has distinct legal requirements compared to other parts of the UK. Further guidance can be found on the HRA website.
Gatekeepers
One route to recruiting vulnerable populations to participate in research is to use gatekeepers. Gatekeepers are mediators who can protect participants from coercion, ensuring that consent is freely given, but can also help facilitate access to particular settings and groups for research. Example gatekeepers include representatives of schools, charities, clinical settings, NGOs etc. Gatekeepers can support ethical research by protecting participants from coercion, identifying potential risks, and advising on mitigation strategies.
Participant facing materials
Recruitment materials must be suitable for the audience and take into account potential vulnerabilities. Materials must provide clear, accurate information without being discouraging or confusing. Researchers are encouraged to use accessible formats such as simplified or age-appropriate language, visuals, translations, or audio versions, depending on the context. For more information, please see our guidance on participant facing materials.
It is also important to consider how to involve and engage members of the public in research design. Involving public representatives from your target population, or individuals with relevant lived experience, can strengthen your study design, improve the clarity and suitability of materials, and enhance the overall quality and relevance of the project.
Confidentiality and disclosure
Researchers must treat all participant involvement confidentially, applying heightened sensitivity when working with vulnerable groups. In situations where confidentiality may need to be breached to prevent harm to the participant or others, researchers must have clear, pre-established protocols. These protocols should set out:
- who may need to be informed (e.g. relevant authorities or professionals), and
- what actions may be taken if sensitive information must be disclosed.
Contacts who may need to be informed about risks of harm include:
- Safeguarding Leads (e.g., UoB Safeguarding Officers).
- Gatekeepers (e.g., care organisations, schools, parents/carers, charities, NGOs)
- Relevant charities and support services
- If someone is in immediate danger, the Police or relevant authorities should be called.
- Your supervisor, line manager, DREO or the research ethics team for guidance (contact research-ethics@bath.ac.uk).
Participants must also be clearly informed of the limits to confidentiality. This must be explained before consent is sought, for example through participant information materials.
Identifying and Mitigating Risks to Vulnerable Participants
Researchers must identify and assess potential physical or psychological risks to participants and implement protocols to ensure safety. This includes planning how to respond if participants become distressed, and identifying appropriate support services, particularly when working with vulnerable individuals. For guidance on completing Health and Safety risk assessments please consult with the Safety, Health, and Employee Wellbeing (SHEW) team and our Research Ethics Open House on this topic. Please remember that completing a risk assessment for research activities is a University requirement.
Reimbursement and Incentives to Vulnerable Participants
Researchers must consider whether and how participants are reimbursed/compensated for their time. Some participants may have specific travel requirements, and additional reimbursements may be required for carers. However, reimbursements may not always be appropriate. For example, offering money to under 18s may encourage younger children to misrepresent their age in order to participate. For more information, please see our guidance on financial incentives.
Relevant Legislation
Research with vulnerable participants must be compliant with relevant legislation, including:
- Human Rights Act 1998 - ensures that rights of vulnerable individuals are protected.
- Children Act 1989 and 2004 - provide the legal framework for the protection and welfare of children.
- Data Protection Act 2018 - governs the processing of personal data, including sensitive data related to vulnerable individuals.
- Mental Capacity Act 2005 - outlines the principles for assessing capacity and making decisions on behalf of those who are unable to do so.
Training
If the focus of your research includes working with vulnerable participants we encourage you to:
- Complete the research ethics training modules developed by UKRIO.
- Explore the following free e-learning resources published by the National Institute for Health and Care Research (NIHR):
- E-learning on inclusive research design
- Informed consent - including adults lacking capacity
- Informed consent with different communities
- Informed consent with children