Approaches to ensure quality of information provision and consent processes for vaccine clinical trial participation in Sub-Saharan Africa: A scoping review

Abstract

Background/Aims

To respect the rights and wellbeing of research participants, these should receive information at all stages of the trial, and procedures should be put in place to ensure a valid consent that promotes an informed, autonomous and voluntary decision-making. This review focuses on the extent and type of evidence available in relation to best practices in the information provision and consent processes for vaccine trials conducted in Sub-Saharan Africa.

Methods

Ancillary studies or evaluations assessing the information and/or consent processes used in vaccine trials implemented in Sub-Saharan Africa were eligible. The databases PubMed, CINAHL, Scopus, Web of Science, African Index Medicus Google Scholar and ProQuest dissertations and thesis citation index and Open Access Theses and Dissertations were searched, without time limits. Following a deductive approach, relevant data were extracted using an extraction tool and categorised into themes.

Results

The review included 46 sources reporting results from 37 studies implemented in 13 Sub-Saharan African countries. The studies covered: community engagement (n = 8); informants (n = 7); messages (n = 7); communication tools (n = 3); community groups (n = 4); consent process (n = 11); comprehension (n = 19) and dissemination of results (n = 4). They mostly represented the views of participants or parents of trial participants; researchers and trial site personnel; and community members and representatives, including those with formal informational roles. The studies showed gaps in information and consent processes leading to a lack of understanding and confusion or suspicion. The involvement of community members in information giving was essential. These were able to communicate in culturally–appropriate ways and also increase trust in the trial.

Conclusions

The studies highlight complexities involved in the information and consent processes for vaccine trials implemented in Sub-Saharan Africa. These processes would benefit from a stronger consideration to the context where research takes place, including culture, language, non-biomedical conceptions and power imbalances. The views from ethics review boards were mostly absent.

Introduction

Providing information to participants and obtaining valid consent are key elements of good clinical trials and essential to respond to the ethical principle of respect for persons. ¹ This requires using adequate language, considering participants’ needs and expectations and the context where research takes place,^2–4 emphasising the importance of community engagement and stakeholders’ involvement^2,4,5 to develop locally acceptable and effective information and consent procedures and materials.^6–8 Nevertheless, implementing adapted information and consent processes remains a great concern in clinical trials in Sub-Saharan Africa. ⁹

Sub-Saharan Africa comprises a diverse and multicultural geographical region, with a vast number of spoken languages. It is also the world’s region with the highest illiteracy and poverty rates according to 2022 data.^10,11 This is combined with widespread lack of adequate access to healthcare in a majority of countries ¹² and an overall low investment in research, including against the prevalent infectious diseases. ¹³ The high burden of potentially vaccine-preventable diseases in Sub-Saharan Africa highlights the importance of conducting vaccine trials in this region.

Information and consent processes include here the multiple time points in which information is provided to participants and communities and understanding and voluntary decision-making promoted. Recent literature reviews focusing on comprehension ⁹ and community engagement practices^14,15 in clinical trials conducted in Sub-Saharan Africa, have highlighted issues around the identification of appropriate stakeholders, adaptation of strategies to existing cultural practices and dealing with potential mistrust against research or the research institution, ¹⁴ as well as the need to address cultural and structural factors impacting on comprehension and ways to enhance and assess understanding. ⁹ Preventive vaccine trials aim to recruit healthy volunteers (i.e. unaffected by the condition under study) that do not receive any direct health benefit from participating, adding particularities to the way stakeholders are involved and communities informed about the trial, including information about risks and benefits. Moreover, in this region, the majority of vaccine trials are sponsored by international organisations. ¹⁶ This puts together two distinct spheres, the researchers linked to a different culture and socio-economic status, and the communities invited to participate, likely unfamiliar with research, who have low access to quality healthcare and who do not receive direct health benefits from trial’s participation.

This review aimed to describe information and consent practices used in vaccine trials that have been evaluated, highlighting research gaps and identifying how these could inform best practices and recommendations that strengthen valid consent in vaccine trials conducted in Sub-Saharan Africa.

Methods

Guidelines provided by the Joanna Briggs Institute ¹⁷ and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) were followed. ¹⁸ The protocol was registered at OSF: https://doi.org/10.17605/OSF.IO/P2ZHR.

Eligibility criteria

Eligible studies evaluated aspects of information and/or consent processes from any stakeholder’s perspectives, in vaccine trials of any clinical phase and vaccine, including mock/hypothetical trials, conducted in Sub-Saharan Africa. Studies focusing on motivation, willingness to participate, or factors influencing participation were excluded. Eligibility was assessed by the main author using a predefined inclusion criteria discussed with the review team. Doubts about inclusion were resolved by consensus.

Types of studies

Qualitative, quantitative, mixed methods and systematic reviews were considered. Opinion papers or comments were excluded.

Search strategy

We aimed to locate published and unpublished studies, without language and time limit. A three-step search strategy was used:

1. Initial search of PubMed using: (Informed consent OR participation OR comprehension OR community sensitization OR engagement OR information dissemination) AND vaccine trial AND Sub-Saharan Africa. Full search strategy developed using keywords in titles and abstracts and index of relevant articles.

2. Search strategy adapted for each database: CINAHL, Scopus, Web of Science, African Index Medicus and Google Scholar. In addition, ProQuest dissertations and thesis citation index and Open Access Theses and Dissertations. The search included keywords, limited to the Title and Abstract field when possible, and related subject headings (Supplementary file, section 1).

3. Reference lists were hand searched and sources citing all included studies were screened using ResearchRabbit, a literature mapping tool, to identify additional studies.

Selection of studies and data extraction

References were imported to Covidence (Veritas Health Innovation, Melbourne, Australia). Titles and abstracts were screened according to predefined inclusion criteria by one reviewer (A.J.G.). Doubts about inclusion were resolved by discussion. All selected sources were assessed by a second reviewer (C.E.F. or E.C.A.).

Data extraction was done by one reviewer (A.J.G.) using a predefined tool developed by all authors and piloted and modified following extraction from the first 10 sources (Supplementary file, section 2). Data related to categorization of themes were extracted by a second reviewer (C.E.F. or E.C.A.). Discrepancies between reviewers were discussed and solved by consensus. Extracted data were also reviewed through regular discussions.

Data synthesis

A basic numerical analysis presented the extent, nature and distribution of included studies. Using qualitative content analysis, ¹⁹ and considering the objectives of the included studies, the studies were categorised deductively into themes and sub-themes, corresponding to a conceptual framework, grounded in recognised/key aspects of information and consent processes that we developed (Figure 1). For each theme, we described the processes used in the trials and included key findings, referring to time when relevant.

Figure 1.

Conceptual framework of the information and consent processes and stakeholders involved in the studies included in the review.

n represents a number of studies including the type of stakeholders.

*Community includes stakeholders involved in information giving, such as leaders and other representatives and members of groups such as community advisory boards and civil society organisations. It also includes community members employed or paid by the trial to deliver information (i.e. Informants).

Results

Study selection

The search was conducted between January and May 2024. In total, 843 records were retrieved and 506 remained after duplicates were removed. Of these, 149 were read in full and 46 included (Figure 2).

Figure 2.

PRISMA-scoping reviews flow diagram.

Characteristics of included studies

We included 43 published articles and 3 thesis reports, one of these later published. These reported on 37 distinct studies, with 7 studies being reported by more than one source. Studies were published between 1997 and 2024 and conducted in 13 countries, with South Africa (n = 11), Kenya (n = 7) and The Gambia (n = 5) representing 56.1% (Figure 3).

Figure 3.

Geographical distribution of the studies included in the review.

South Africa n = 11 (26.8%); Kenya n = 7 (17.1%); The Gambia n = 5 (12.2%); Tanzania n = 5 (12.2%); Sierra Leone n = 3 (7.3%); Mali n = 2 (4.9%); Uganda n = 2 (4.9%); Democratic Republic of the Congo n = 1 (2.4%); Malawi n = 1 (2.4%); Ghana n = 1 (2.4%); Liberia n = 1 (2.4%); Senegal n = 1 (2.4%). Four studies included 2 countries.

Context

Studies were nested in an estimated 37 trials investigating vaccines against 14 different diseases including HIV (n = 10), malaria (n = 7) and Ebola (n = 5). Trials recruited infants or children <5 years of age (n = 18) or adults only (n = 19), with 2 enrolling women or pregnant women only. They covered all stages of clinical development. Two were mock trials. Sponsors included international organisations, with three trials nationally co-sponsored (Supplementary file, section 3):

Study methodologies. Studies were quantitative (n = 12),^20–31 qualitative (n = 19)^32–59 or mixed-methods (n = 5).^33,60–64 One was an evaluation. ⁶⁵

Themes. Studies covered eight identified themes (Figure 4 and Table 1). Studies published prior to 2001 focused on the consent process and the quantitative assessment of understanding. Assessment of community engagement activities started in 2012. Studies included a wide range of trial’s stakeholders (Figure 1).

Figure 4.

Themes identified in the included studies, per year and total.

^aAlthough we took a broad definition of community engagement, activities assessed by the studies fall under community sensitization, understood as the process of providing information about a trial to gain community’s support.

^bInitially we separated informants, understood as any person providing information, from community informants. Nevertheless, these were grouped as in all studies assessing informants, these had close links with the community.

Table 1.

Evidence table.

	Authors	Objective	Themes	Methods	Participants	Main findings	Limitations
1	Afolabi 20 ;pneumococca,The Gambia (2014)	Develop a standard Digitised Informed Consent Comprehension Questionnaire (DICCQ)	Comprehension	Quantitative:Questionnaire	Parents of trialparticipants(n = 250)	DICCQ demonstrated good internal consistency and convergent, discriminant and discriminative validity	Results may not be generalisable to other settings. Lack of a gold standard to assess comprehension limited the evaluation of the tool.
2	Alenichev 32 ;Ebola, Liberia (2020)	Explore participants’ understanding regarding the meaning of an ‘Ebola vaccine’	Comprehension	Qualitative:Semi-structured interviews; Group discussions	Trial participants(n = 25)	Information not always understood as intended and nearly all informants expressed heterogeneous perspectives. From participants’ perspectives, their interpretations are not misconceptions.	Limited to what informants said, data represents stated beliefs rather than actual practices
3	Angwenyi 33 ;malaria, Kenya (2013)	Document experience of including CHW in community engagement activities	Stakeholders; Community engagement; Information giving; Comprehension -	Mixed methods: In-depth interviews; Group discussions; Structured observation; Semi-structured household survey	Parents of trial volunteers; Parents of trial participants; Trial community workers; Staff involved in designing and implementing community engagement activities (N = 236 + observed over 15 activities)	Involvement of CHWs perceived as important. However, CHWs emphasised study benefits, exerting some sort of pressure. CHWs expressed the need for more training. A fair compensation system was also lacking.	Study conducted alongside and feeding into ongoing CE for the trial, and by social scientists employed by the research organisation, could have reduced independence and critical analysis.
	Angwenyi 60 ; malaria, Kenya (2014)	Analyse processes of community engagement, including community members’ perceptions. Evaluate participants’ understanding 1 year after recruitment				CE activities adapted in response to concerns and rumours. Essential to incorporate pre-existing decision-making structures. Translation of research terms was complex. CE activities helped clear pre-existing concerns and misconceptions, raised awareness and built trust. But important gaps in understanding remained. Feedback meetings provided opportunity to reiterate study aims
4	Campagne 34 ; meningococcal meningitis, Niger (2003)	Evaluate the reasons of a recruitment drop by observing each of the phases of the informed consent procedures	Information giving; Consent	Qualitative: Informal interviews; Questionnaire; Observation	Parents of trial participants; Trial personnel (number not indicated)	Absence of validated translation of information sheets caused several problems. The consent procedure also brought up difficulties, as participants’ preferences and sponsor’s requirements did not align.
5	Chantler 36 ; rotavirus and malaria, Kenyaa (2012)	Review the practice of community engagement from different angles	Community engagement; Stakeholders	Qualitative: Semi-structured interviews; Focus group discussions, Participant observation and informal conversations	Community representatives; Community members; Parents’ trial participants; Researchers; CAB members; Village reporters (N = 122)	Distinction between the local community where research takes place and the research community. Community characterised by ‘cultural’ beliefs and practices considered contrary to the goals of biomedical research.	Challenges identified may be limited to the context where the research was conducted and warrant more in-depth examination.
	Chantler 35 ; paediatric vaccine trials, Kenya (2013)	Exploring how community engagement is practised and the role of village reporters				People enrol in a trial because they trust VR. VR emphasised positive messages, raising concerns of undue influence. VR wants to do well towards the research organisation, which also brings them a type of status in the community.
6	Dada 37 ; Ebola, Sierra Leone (2019)	Explore community engagement approaches implemented in 2 trials post-Ebola epidemic	Community engagement	Qualitative: In-depth interviews; Focus groups discussions	Trial community workers; Community liaison team and Social Science team (N = 15 participants + 3 FGD)	Key aim of the CE programme was to establish trust. Trust was established by ‘Four Rs’: Reciprocity or hearing and addressing the community; Relatability achieved by incorporating community informants, Relationships and Respect.	Study achieved data saturation, but sample size was small. Some responses may have been biased as participants were staff in the trials and may have responded more positively.
7	Dietrich 38 ; HIV, South Africaa (2022)	Explore CAB members and researchers’ perceptions of community engagement practices	Community engagement; Stakeholders	Qualitative: In-depth interviews; Focus group discussions	Researchers; Trial community workers; CAB; Community engagement staff, research assistants, recruiters and project coordinator (N = 27)	CE is about educating people in the community by linking with external stakeholders CABs can act as a link between researchers and the community. CAB involvement is crucial for gaining trust, building relationships with the community and understanding research.	Results may not be generalisable to other sites. Potential lack of criticism from participants, may have brought social desirability bias
8	Ellis 21 , malaria, Mali (2010)	Assess understanding just after consent was completed	Comprehension	Quantitative: Questionnaire	Trial participants; Parents of trial participants (N = 789)	Overall good level of understanding (adults and parents/guardians answered correctly 85% of the time). Findings suggest that illiteracy should not be a barrier to valid consent.	Questionnaires were intended for teaching participants rather than for collecting data. Lack of standardised instruments makes precise comparison with other studies impossible.
9	Enria 39 ; Ebola, Sierra Leone (2016)	Examine community and participant perceptions and experiences, including rumours and concerns	Community engagement	Qualitative: In-depth interviews; Focus group discussions; Exit interviews	Trial participants; Key stakeholders (N = 42)	Three emerging themes shaped CE: power or disputes over authority and recognition of leadership; fairness and perception of procedures; and trust, involving understanding public perceptions, rumours and concerns and creating multiple forums for dialogue	Findings are very specific to the context
10	Essack 40 ; HIV, South Africaa (2012)	Explore the perspectives and experiences of civil society organisation representatives regarding negative HIV trial results	Stakeholders; Dissemination	Qualitative: In-depth interviews conducted by telephone	CSO representatives (N = 14)	Negative results received with disappointment and misunderstandings, particularly due to lack of understanding of research and the possibility of trial discontinuation	Small sample size, limiting representativeness.
	Koen 46 ; HIV, South Africa (2013)	Assess civil society organisation perspectives on the impact of negative trial results on stakeholder engagement				Importance of transparent and ongoing communication from trial outset. CSOs and CAB can play a role in informing community members.
11	Evangeli 22 ; HIV, South Africa (2013)	To investigate the impact of message framing on participants’ willingness to participate	Information giving	Quantitative: Questionnaire	Trial volunteers (N = 283)	Certain gain-framed messages were more likely to lead to hypothetical vaccine trial participation than certain loss-framed messages.	Sample not adequately representative of the individuals that would be approached to participate in vaccinate trials.
12	Fairhead 41 ; pneumococco, The Gambia (2006)	Assess representation of the consent processes: how fieldworkers describe the practices implemented and how parents interpret interventions	Consent; Stakeholders; Comprehension	Mixed methods: Interviews; narrative interviews; Focus group discussions; Questionnaire; Participant observation	Health care workers; Parents of trial participants; Trial community workers; Fieldworkers; Community health nurses; Village health workers; fieldworkers and supervisors (N => 850)	Fieldworkers were able to select strategically which aspects of the trial to explain or emphasise. Free treatment was a central part of the local understanding of the trial for fieldworkers and families.	Finding may represent the context where the study was conducted.
	Fairhead 61 ; pneumococco, The Gambia (2006)	Explore understanding and interpretation of research practices and procedures once study recruitment ended				Participants had a low understanding of the aim of the trial as explained by researchers. To gain insight into the alternative explanations offered by participants, it is important to consider local health practices and local understandings and experiences of trial’s procedures.
13	Gikonyo 62 ; malaria, Kenya (2008)	Document participants’ understanding and concerns at recruitment. Explore community members’ views about information given and consent process. Gather community members views about involvement of fieldworkers and expectations about dissemination of results.	Consent; Stakeholders; Comprehension; Dissemination	Mixed methods: Interviews; Focus group discussions; Questionnaire;	Parents of trial participants; Community members; Fieldworkers (N = 192 + 11 FGD)	Different ways of providing information about the trial complement each other. Trial described as a form of health assistance, even for those who apparently understood the trial’s aims. At trial’s end, participants requested to get individual results and health assistance.	Interview questions may not have fully captured participant understanding; because of the tool itself, or the way and point at which it was administered. The findings may be specific to the study population and to the socio-cultural and institutional context of the study
	Molyneux 64 ; malaria, Kenya (2007)	Assess views of participants regarding the use of a formal check to assess understanding				29% to 85% of correct answers for key study details. 35% correctly responded about the trial’s aim. The quiz provided a chance to clarify information but caused concerns and was associated with rumours circulating in the community.
14	Gikonyo 42 ; malaria, Kenya and Tanzania (2013)	Explore feedback of participants and researchers about the dissemination of aggregate study findings	Dissemination	Mixed methods: In-depth interviews; Focus group discussions; Observation	Community members; Parents of trial participants; Researchers; Fieldworkers (N = 40)	Negative trial findings received with disappointment and misbelief. Participants requested written individual health reports to take home.	Findings likely relevant for community-based trials involving intense relationships between research teams and participants.
15	Iseselo and Tarimo 43 ; HIV, South Africa (2024)	Find out volunteers’ comprehension of informed consent and voluntary participation	Consent; Comprehension	Qualitative: In-depth interviews	Trial participants (N = 20)	Participants’ understanding of the purpose affected by desire for HIV risk reduction. High value given to privacy and confidentiality.	Results may not be transferred to other sites
16	Jalloh 44 ; Ebola, Sierra Leone (2019)	Examine perceptions of an experimental vaccine to guide ethical communication of risks and benefits. Explore concerns and information gaps	Information giving; Comprehension	Qualitative: In-depth interviews; Focus group discussions	Community representatives; Community members; Health care workers (N = 66)	Lack of understanding of experimental vaccine and differences with approved vaccines. HCWs and frontline workers considered as trusted sources to communicate about experimental vaccines.	Answered may have been influenced by social desirability bias. Limited generalisability of findings.
17	Kamuya 45 ; malaria, Kenya (2015)	Assess the emergence of ‘silent refusals’ and how fieldworkers handled these	Consent; Stakeholders	Qualitative: In-depth interviews; Focus group discussions; Natural group discussions; Participant observation	Community members; Researchers; Trial community workers (N = 56)	‘Silent refusals’ as a way of being polite to a respected person, safeguarding relationships with the research organisation or not wanting to offend fieldworkers. Also, a way to delay decision-making, when unsure or wanting to check credibility of information. Fieldworkers responded with extended discussion, contributing to positive relationships and trust.	Included participants from a study unrelated to vaccination.
18	Krosin 23 ; malaria, Mali (2006)	Identify deficits in comprehension of information just after providing consent	Consent; Comprehension	Quantitative: Questionnaire	Parents of trial participants (N = 163)	90% of respondents did not understand withdrawal, 93% did not know about side effects, and 74% did not understand they were enrolled in an investigation as opposed to receiving therapy.	Participants may not have understood the survey instrument.
19	Lang 65 ; malaria, Kenya and Tanzania (2012)	Compare approaches used for community sensitization strategies	Community engagement	Evaluation: Reviews of documents; Sharing community sensitization strategies and experiences	Research team	The different types of meetings (community, household and site) allowed for different interactions and complemented. Who provides the information may influence clarity and trust.	Enrolling a trial dependent on a wide range of factors, not limited to communication.
20	Leach 63 ; Haemophilus influenzae, The Gambia (1999)	Examine the attitudes towards consent and evaluate the informed consent process used, within 1 week of providing consent	Consent; Comprehension	Mixed methods: Semi-structured interview	Trial volunteers; Parents of trial participants (N = 189)	Variable level of knowledge for different questions. 90% understood the purpose of the vaccine, but only 10% randomisation. Parents were unable to validate information from other sources and depended largely on trust.	Findings limited to the context.
21	Lindegger 24 ; HIV, South Africa (2006)	Develop and compare 4 alternative methods to assess understanding (self-report, true/false, vignettes and narrative)	Comprehension	Quantitative: Questionnaire	Trial volunteers; Trial participants (N = 59)	By different methods understanding was 86% self-reported, 82% checklist, 69% narrative and 67% vignette	The results may have been altered by a sequence effect. Not random sample.
22	Mapetla 25 ; HIV, South Africa (2022)	Establish preferences in communication methods to remind participants about their scheduled visits and establish interest in receiving study information via cell phones	Information giving	Quantitative: Questionnaire	Trial participants (N = 90)	Communication preferences were calls by site staff (80%), SMS (16%) and WhatsApp (3%). 97% of participants interested in receiving regular general study information updates via their cell phone.	Absence of data for those that withdraw from the trial.
23	Mboizi 26 ; pneumococco, The Gambia (2017)	Assess parents of participants’ recall of information using a speaking book at the consent visit and at 3 months follow-up	Information giving; Comprehension	Quantitative: Questionnaire	Parents of trial participants (N = 409)	Trial participants receiving a speaking book had a good knowledge of the trial procedures at the start of the trial at 3 months follow-up. The speaking book was liked by most women and was shared with family and friends.	Lack of comparator group. The study was conducted in a community with a long history of exposure to research. Only included women who had good comprehension at baseline as this was a requirement to enrol the trial.
24	McGrath 27 ; HIV, Uganda (2001)	Assess knowledge about vaccine and vaccines trials after the consent visit and 2 years later	Comprehension	Quantitative: Structured interviews	Trial participants (N = 1182)	At baseline, the definition of placebo was partially understood by 42% and 27% gave incorrect answers. Understanding increased after educational sessions with 71% understanding aspects of placebo.	Focus on the military, results may not be generalisable
25	Meiring 48 ; typhoid, Malawi (2019)	Review the effectiveness of engagement activities	Community engagement	Qualitative: Focus group discussion; Reflection meeting	Frontline trial staff (fieldworkers and research nurses) (N = 6)	Discussions with the community advisory group and other stakeholders helped the trial team identify appropriate engagement activities. Meetings created space for questions and dialogue.	Findings based on trial team’s perspectives, did not include feedback from community
26	Minnies 28 ; tuberculosis, South Africa (2008)	Determine study participants’ recall and understanding of items discussed during the consent procedure and quality of the informed consent	Comprehension	Quantitative: Questionnaire	Parents of trial participants (N = 192)	On the consent day, most participants obtained scores more than 75% for understanding and 66% for recall. Level of education was not linked to understanding.	Difficulties in measuring understanding.
27	Moodley 29 ; influenza, South Africa (2005)	Assess recall of information 4 to 12 months after trial participation	Comprehension	Quantitative: Questionnaire	Trial participants (N = 334)	95% understood that the trial was not part of routine care, 21% correctly interpreted randomisation and 19% placebo. 93% of participants considered the information in the leaflet easy to understand.	Difficult to draw a distinction between understanding and recall.
28	Nkosi 49 ; Covid-19; South Africa (2022)	Explore participants’ perceptions and experiences with the informed consent process	Comprehension	Qualitative: Semi-structured interviews; Focus group discussions	Trial participants (N = 25)	Participants expressed an overall good understanding of the purpose of the tria, but some concepts were misunderstood.	Main investigator was involved the recruitment and consent for the trial.
29	Preziosi 50 ; pertussis, Senegal (1997)	Determine the feasibility and validity of seeking individual informed consent	Consent	Qualitative: Interviews	Parents of trial volunteers (N = 55)	Mothers were confused about being asked for individual consent, which they believed had already been given at information meeting. Village meetings facilitated individual information.	Individual informed consent was not a standard practice when the study was implemented.
30	Rautenbach 51 ; HIV, South Africa (2015)	Explore representations of critical research-related concepts among key stakeholders	Information giving; Comprehension	Qualitative:	CAB; Educators/outreach workers and counsellors (N = 34)	Inaccurate representations of research concepts. Research site perceived as mysterious, untrustworthy and possibly dangerous. Participants as heroes, heroic martyrs, also as guinea pigs, and researchers as ‘brainwashing’ or exploited.	Study conducted at one site; findings might not be generalisable. Did not use observation and relied on self-reports. Did not include trial participants.
	Slack 54 ; HIV, South Africaa (2016)	Describe strategies used to communicate research concepts to prospective participants				Communicators used different strategies to enhance comprehension. They also appeared as striving to reach other important goals such as trust.
	Matandika 47 ; HIV, South Africa (2017)	Explore how trial information was communicated to potential participants				Communicators in their interactions, addressed information, emotional and relational issues. Recognised cultural needs and preferences.
	Thabethe 56 ; HIV, South Africaa (2018)	Identify key attributes that render a communicator of trial information more or less trustworthy. Identify information component that are the focus of mistrust				Trusted communicators are close to communities and unaffiliated to the researchers.Information is not trusted when it is contradictory between different communicators, not congruent with everyday observations or linked/supported existing suspicions.
31	Reddy 52 ; HIV, South Africa (2010)	Examine the purpose, structure, representativity and role of CABs	Information giving; Stakeholders	Qualitative: Semi-structured interviews; Focus group discussions	Researchers; CAB; Community liaison officers and recruiters (N = 72)	CABs can safeguard community’s interests, protect participants, provide information and act as a link with communities. They did not perceive recruitment as their role. Expressed frustration at their dependence on the researchers and limited role.	Findings may be limited to the context.
	Sifunda 53 ; HIV, South Africaa (2014)	Examine methods of recruitment used to enrol participants in HIV vaccine trials in South Africa				Staff members’ dual role as educator and recruiter perceived as problematic. This, conflict was exacerbated by the personal relationships with the community members they were trying to recruit.
32	Ssali 55 ; Invasive Group B Streptococcus Disease, Uganda (2024)	Learn about information requirements during the consenting process. Explore expectations about the consent process in pregnancy.	Informationgiving; Consent	Qualitative: In-depth interviews; Focus group discussions	Trial participants; Health care workers; Women not participating in the trial; Community stakeholders; Partners to women in the trial (N = 56)	Women valued the opportunity to share study information with their networks such as partners/husbands. Many participants understood the significance of signing the consent form and the importance of retaining the information sheet for future reference.	Study conducted in one hospital may not be representative. Participation of few stakeholders.
33	Ward 57 ; Malaria,Ghana and Tanzania (2018)	Presents key stakeholders’ perspectives, researchers responsibilities towards communities and participants at the end of a trial	Dissemination	Qualitative: Semi-structuredinterviews	Parents of trial participants; Researchers; Clinicians; Health care personnel; Sponsor/funders; ERB members (N = 52)	Trial’s end had consequences on health services that needed to be addressed. Expressing appreciation and thanking participants and communities was seen as a respectful disengagement and vital for maintaining trust.	Study involved views of different stakeholders, but some were underrepresented.
34	Watermeyer and Penn 58 ; HIV, South Africaa (2008)	Investigate the consent process by examining the communication practices and issues in consent sessions	Consent	Qualitative: Semi-structured interviews; Observation; Ethnographic notes and video	Trial volunteers; counsellor providing informed consent (N = 3)	Consenter primarily read the consent document with little interaction and few questions. Use of ‘personalised moments’, in which the counsellor showed proximity to the participant, had a positive effect.	Observation of the informed consent process conducted by 1 counsellor.
35	Wyss-van den Berg 59 ; Malaria, Kenya and Tanzania (2020)	Elucidate themes from the complexity theory that shape the clinical trial ecosystem	Community engagement	Qualitative: Semi-structured interviews	Parents of trial participants; Researchers (N = 66)	Engagement occurs through numerous and diverse interactions between researchers and caregivers, not limited to formal activities. Communication reduced spread of rumours, strengthened understanding and brought trust.	Study conducted in a context with long exposure to research.
36	Yauba 30 ; pneumococco, The Gambiaa (2013)	Assess effectiveness of obtaining informed consent using a new procedure recommended by the ethics committee	Information giving; Comprehension	Quantitative: Questionnaire	Parents of trial participants (N = 1200)	Just after consent, 90.5% responded to all questions correctly. Understanding was associated with younger age; there was no association with educational level.	Participants have been exposed to research for several decades. The questionnaire used a limited set of questions.
37	Zola Matuvanga 31 ; Ebola, Democratic Republic of the Congo (2024)	Assess participants’ retention and understanding of the trial information at screening and 1 and 2 years after enrolment	Comprehension	Quantitative: Questionnaire	Trial volunteers; Trial participants (N = 699)	Significant decrease in knowledge related to purpose of the trial, safety risks and voluntary participation. Baseline understanding may be a literal reminder prior to signing the consent form.	True/false questions may have led to an overestimation of comprehension at baseline.

Community engagement

Community engagement activities were assessed in four paediatric vaccine trials in Kenya, Tanzania and Malawi,^36,59,60,65 HIV trials in South Africa ³⁸ and during the Ebola outbreak in Sierra Leone.^39,66 These were published between 2012 and 2023. In these, community engagement consisted of a multi-step process. Engagement with community leaders, considered as gatekeepers, was generally a first step^{36,48,59,60,65} followed by community meetings^{36,37,39,60,65} at times assisted by leaders or other representatives.^36,39,60 Engagement activities were also conducted to small groups at the community, ⁴⁸ health facilities^36,60 or during household visits.^36,39,60,65 These were conducted by community members assigned with informational roles,^{36,39,48,60,65} and at times involved community advisory boards (CABs).^36,38

Community engagement was directed to sensitise about the trial and promote understanding. This included handling rumours and concerns in five studies.^{39,59,60,65,66} Trust building also appeared a key goal of community engagement in the eight studies. Understanding and trust were enhanced when information was provided by community sources,^36,39,48,65 who shared cultural and social norms. ⁶⁶ This emphasised the importance of incorporating appropriate community stakeholders,^{36–39,48,59,60,65} identifying recognised leaders and considering power dynamics. ³⁹ Nevertheless, this required caution as leaders could exert pressure to enrol. ⁶⁰ Interactions with communities also played a role.^37,39,59,60 These included establishing an inclusive dialogue, hearing and addressing communities’ concerns, described as essential in an Ebola vaccine trial.^37,39

Community engagement was a complex process, framed by social relations and contextual specificities, including disparities in access to knowledge and resources. ³⁶ In this way, community engagement activities were not limited to formal plans, but involved numerous and diverse interactions that occurred between researchers and community members through the trial, ⁵⁹ influenced by personalities, backgrounds and expectations,^36,60 and modified in responses to emerging issues, including rumours and concerns.^60,65

Informants

Seven studies published between 2006 and 2018 assessed attributes and role of employed^41,45,53,62 or hourly paid ³⁵ field personnel, community health workers ³³ and educators and CAB members^47,54,56 in providing information to communities about the trial. Most of these informants were from the community where the trial took place and all shared culture and language. Researchers, communities and participants considered this proximity as facilitating communication in five studies.^{33,35,41,45,62}

Along with providing information, informants aimed to enhance credibility and trust in the research and researchers in five studies.^{33,36,45,47,54,56,60,62} Factors such as familiarity or shared identity,^54,56 and perceived independence to the researchers were attributed to ‘trustworthy’ communicators in HIV trials. ⁵⁶ Trust was also built by being honest, transparent, consistent and reliable ⁵⁴ and by exhibiting concern and fairness. ³³ Trust building efforts appeared to respond to high levels of suspicion with blood sampling for instance being a key issue.^{36,41,45,56,60,62} To reduce suspicion, informants at times, implicated credible sources in information giving, including community leaders and ex-participants.^33,54

Informants tried to provide adequate information, but were at times ill-equipped to respond to questions and concerns.^33,62 In five studies they were found to use their own tactics to deliver information and increase trial’s acceptability, including using familiar examples, ⁵⁴ emphasising benefits and positive aspects,^33,35,41,62 building strong links with influential figures ⁴¹ and lengthening interactions with volunteers that appeared reluctant to make a decision about participation. ⁴⁵ Their close proximity to communities also brought up some challenges, including requests for assistance from community members. ³⁵ Informants, moreover, felt accountable in case of undesirable outcomes and perceived their informer’s and recruiter’s roles as conflictive, highlighting limits of adequately educating volunteers who knew little about research in a given timeframe.^36,53

Messages

Seven studies assessed aspects related to the messages.^{22,30,34,44,47,54–56,60} Two studies highlighted the importance of adapting messages to participant’s needs,^44,54,55 for instance differentiating between experimental and approved vaccines highlighted in an Ebola vaccine trial. ⁴⁴ Pregnant women in Uganda highlighted the importance of clear and non-technical language to inform about risks and benefits, purpose of the study, side effects and withdrawal options. ⁵⁵

One study suggested that messages framed as a gain (e.g. ‘If I take part in this study, I will have access to a risk-reduction counsellor and regular HIV testing’), as opposed to a loss (e.g. ‘If I do not take part in this study, […]’), could lead to higher willingness to participate. ²²

Certain messages related to experimental vaccines and use of blood were sources of mistrust or suspicion in HIV trials.^47,56 In these, messages were more likely to be trusted if they were congruent with everyday observations and community’s understanding, and consistent within different communicators. ⁵⁶ Similarly, referring to safe, effective vaccines close to people’s experiences appeared to instil trust in medical research.^47,54

Translation challenges were highlighted in three studies.^30,34,60 A study in Niger, published in 2003 reported how the lack of validated translation of the consent information generated adaptations by the consenter, aiming for a positive image. ³⁴ Translated terms in approved information sheets, such as compensation and randomisation, were reported to lead to different interpretations and were associated with rumours and concerns in study from 2014. ⁶⁰ To enhance understanding and avoid adaptations, a study in Ghana evaluated a new procedure, where consent forms were written in English, and a scientific committee provided recommendations on the oral translation. ³⁰

Communication tools

Communication tools were the focus of two studies.^25,26 An audio-visual tool (i.e. speaking book) given to families participating in a paediatric vaccine trial was highly used and shared with friends and family. ²⁶ The use of mobile communication was assessed in an HIV trial. ²⁵ In this, 80% of participants preferred being called than messaged and 97% welcomed receiving regular updates. ²⁵

Participants of one study suggested using short videos or audio, posters and flyers and to illustrate information notices. ⁵⁵ The use of radio, television and social media, was also encouraged. ⁵⁵

Community groups

Four studies published between 2010 and 2023 assessed the roles of CABs,^36,38,52 and civil society organisations (CSOs). ⁴⁶

Community advisory boards

CABs’ roles were addressed in three studies nested in HIV trials^38,52 and malaria and rotavirus paediatric trials. ³⁶ These involved providing advice to researchers about community norms and expectations; disseminating information; assisting in creating a supportive community environment and feeding back on community’s concerns; and reviewing participant information leaflets and consent documents.^38,52 Their role in recruitment was disputed in a study published in 2010, with researchers expecting CAB’s assistance in recruitment and advisors considering this outside their boundaries. ⁵²

CAB members felt responsible for presenting a positive image of the research organisation, overcoming suspicion and promoting acceptance. ³⁶ This risked being viewed as ‘sell-outs’ or ‘brain-washed’. ⁴⁷ The dependence of CABs on the trial, including financial support and training, was perceived as compromising their independence and actions in two studies published in 2010 and 2012.^36,52

Civil society organisations

In HIV trials, CSO members viewed themselves as having informational and oversight roles, ensuring, for instance, that research benefitted communities and the voluntariness of consent. ⁴⁶ They considered themselves as independent from the trial team and able to enhance community representativeness. ⁴⁶ CSO members called for a transparent and inclusive involvement from trial’s onset, avoiding requests solely in case of difficulties. ⁴⁶

Consent

Eleven studies published between 1997 and 2024 evaluated the consent processes.^{23,34,41,43,45,50,54,55,58,62,63} In this, consent was taken by researchers^23,45,55 or fieldworkers, ⁴¹ at the study site ⁴⁵ or volunteer’s home. ³⁴ Consent documents were written in English/French and the local language.^41,50,62,63 At times an oral translation to the local language was used.^30,34,58

Consent process

The consent session was observed in two studies.^23,58 In a paediatric malaria vaccine trial in Mali, the consenter provided an oral explanation to groups of 2 to 4 parents, taking breaks to summarise and allow questions. ²³ In an HIV trial in South Africa, the counsellor took extensive, uninterrupted turns reading the consent document or explaining concepts, with little input from the volunteer. ⁵⁸ To increase rapport, the counsellor at times relaxed from the formal role, by, for instance, commenting on the length of the document, and this appeared to increase participants’ comfort and trust. ⁵⁸ Sessions lasted between 40 min and 1 h.^23,58

Consent counsellors from HIV vaccine trials requested participants to explain concepts in their own words and switched languages to accommodate participants’ preferences. ⁵⁴ Counsellors, however, reported limits in promoting understanding due to the volume of information and limited time. ⁵⁴ They also found difficulties promoting voluntariness once information about compensation was disclosed. ⁵⁴ These counsellors viewed consent as an ongoing process, with multiple opportunities to reinforce information. ⁵⁴

Participants’ perceptions

Six studies assessed participants’ perceptions on the consent session.^{34,43,50,55,62,63} The three older studies published between 1997 and 2003, presented signing the consent as potentially causing mistrust or confusion, with parents questioning the motives of the investigator and their responsibility if something happened to the child ⁶³ or not understanding why a signature was required.^34,50 In two studies from Kenya and Tanzania published in 2008 and 2024, filling and signing a form was perceived as binding, limiting voluntariness ⁴³ and protecting researchers. ⁶² However, in a Ugandan study from 2024, pregnant women considered signing as common and a proof of understanding and willingness to participate. ⁵⁵ Assessment of literacy and requirement of a witness were questioned in two studies, with participants considering these procedures inappropriate in a study from 2003, ³⁴ highlighting that literacy did not reassure understanding in 2024. ⁵⁵ A study from 2024 stated that the consenters’ counselling skills helped participants understand procedures and develop trust. ⁴³

Consent decisions were perceived as having wide implications, providing, for instance, access to medical service. ⁴¹ Moreover decisions were embedded in power dynamics and relationships, influenced by perceptions of respect and politeness towards heads of household and informants. ⁴⁵

Trial participants provided suggestions to improve the consent process in two studies published in 1999 and 2024. The most recent suggested that consent could be improved by providing clear information, free from technical language. ⁵⁵ The older study highlighted a polite and respectful process, without force. ⁶³ Allowing time to share information and involving others in the decision-making, particularly husbands, was highly valued.^55,63

Comprehension

A total of 19 studies published between 1999 and 2024 assessed comprehension of research-related concepts.

Measuring understanding

Fourteen studies assessed understanding using different questionnaires and types of questions, including true/false, multiple choice and open-ended. These were administered to trial participants,^{20,21,24,27,29,63} their parents,^{23,26,28,30,60,61,64} or less frequently to volunteers or refusals.^24,31,63 Understanding was most often assessed on the consent day,^{21,23,26–28,31,64,30} or 3 months to 2 years after initial consent.^{27,29,31,60,61} Three studies assessed understanding at two points.^26,27,31

Overall correct responses varied from 67% to 99%.^{21,24,26,28,30} Understanding of specific questions varied, with for instance placebo correctly understood by 10% to 49% of participants^27,29,63 and trial’s aim by 35%. ⁶⁴ In two studies, understanding decreased over time.^26,63 Increased exposure to information, including repeated explanations and giving information sheets to take home, was suggested to increase understanding in seven studies.^{26–28,30,31,49,63}

A study found that true/false questions overestimated comprehension, with open-ended or multiple choice providing a more accurate account. ²⁴ Another study stated that measurement of understanding should be complemented with qualitative assessments. ⁶⁴ One study found that a digitised, audio-recorded questionnaire including questions in different formats could increase objectivity and overcome challenges related to lack of standardised written languages. ²⁰

Interpretations

The eight studies assessing understanding using qualitative methods described challenges in the representation of key information.^{32,43,44,49,51,60–62,64} For instance, a malaria trial was generally described as a form of healthcare assistance. ⁶² Differences between experimental and approved vaccines were presented as a source of misunderstanding in Ebola and HIV vaccines trials.^{43,44 43} Trial procedures were also associated with misunderstandings, with confidentiality, for instance, being hardly understood in a context where participation was known by community members. ⁶⁰

Four studies highlighted how information was influenced by local knowledge and practices.^32,51,60,61 In this way, health benefits attributed to the placebo in an Ebola vaccine trial were influenced by local understanding of injections and immunisation. ³² Understanding of trial’s procedures was also affected by people’s particular circumstances, including socio-economic, leading for instance to blood-stealing rumours in The Gambia. ⁶¹

Dissemination of findings

Four studies assessed dissemination activities.^{40,42,46,57,62} Results were disseminated by community meetings,^42,46 at times supplemented by leaflets. ⁴² Dissemination of findings was understood as an ongoing process building up on initial community engagement activities.^40,42,46 Two studies addressed the communication of negative findings.^40,42,46 These were received with disappointment by community and CSO members, highlighting the need to enhance understanding during trial’s implementation.^40,46

Three studies described trial’s end as a concern for participating communities as this was associated with interrupted access to improved healthcare^42,57,62 and other benefits, such employment. ⁴² Dissemination activities involved negotiation of post-trial benefits and expectations.^57,62 Participants perceived dissemination activities as a sign of respect and appreciation for their involvement.^42,57,62 Ethics review board (ERB) members emphasised the importance of post-trial access. ⁵⁷

Discussion

This review included studies assessing information-giving and consent processes used in vaccine trials implemented in Sub-Saharan Africa. The studies covered a variety of processes, ranging from community engagement to dissemination of results, including perspectives from participants, community stakeholders and researchers. The review highlights that informed consent for vaccine trials in Sub-Saharan Africa is not limited to a minimalist, dyadic model involving a researcher and a volunteer but involves various stakeholders. ⁶⁷ Community leaders provided access to the community but also participated in sensitization activities and acted as credible sources. Informants from the community were able to facilitate communication and created positive relations. The involvement of community stakeholders appeared to increase trust. Nevertheless, the review highlights critical gaps in comprehension of key trial information after consent, questioning the adequacy of processes and extent of informed decision-making.

Considering the elements of our conceptual framework, comprehension received most attention, followed by consent and community engagement activities. Except for a formative assessment guiding communication for an Ebola vaccine trial, ⁴⁴ included studies retrospectively assessed processes, lacking information on the design and adaptation of processes, including development and pilot of consent documents. Most studies on consent reported perceptions and only two studies observed the process, providing little insight on related challenges. In relation to stakeholders, most studies included trial participants. ERB members were only involved in one study, and didn’t address ERB’s approval and oversight roles.

Despite these gaps, the studies highlight important recommendations to strengthen information provision and consent processes in vaccine trials in Sub-Saharan Africa (Table 2). These recommendations are aligned with international research guidelines^1,3,4 and are applicable to clinical trials more broadly. Nevertheless, they also address unique challenges related to vaccine trials in Sub-Saharan Africa, particularly in relation to the recruitment of healthy volunteers from the communities, the implication of community stakeholders and potential effects of disparities between communities and researchers.

Table 2.

Main recommendations highlighted from the studies included in the review to strengthen the information provision and consent processes in vaccine trials in Sub-Saharan Africa.

In these settings, the application of community and participant-centred principles that promote participants’ and communities’ views and needs would entail establishing an open dialogue between researchers, community representatives and potential volunteers in all stages of the vaccine trial, promoting an equal opportunity of expression,^36,41,59 taking into account local framings of disease and health-related knowledge.^32,48,51 The consideration of social relations and power, questioning who are considered as legitimate representatives’ and how these, in turn, act towards the interest of the community, should also be addressed. ¹⁵ Community stakeholders charged with information provision, including leaders and informants, should receive adequate training and support, along with continuous monitoring^{33,35,54,58,62,65} and adequate tools that help explain complex information in local languages. The dual role of informing and recruiting should be considered, addressing perceived conflicts and consequences. ⁵³ Moreover, attention should be directed towards ensuring that local practices, such as involving community leaders, do not threaten ethical standards and that consent remains an individual’s informed voluntary decision.

Information and consent processes should be considered continuous,^38,43,60 adapting messages in response to participants and communities’ evolving reactions and needs, assessing comprehension and desire to continue participation. Information should include post-trial access plans. Continuous, adapted communication should improve understanding and reduce feelings of unmet expectations at trial’s end that could negatively impact future research. However, this contradicts the rigidity of informed consent documents, difficult to modify once approved. ⁶⁸ ERBs’ role in information and consent process should be expanded to include continuous oversight and monitoring and facilitation of participant-centred practices. Roles could be coordinated between in-country and sponsor’s country committees.

Over the years, different tools have been proposed to assist in tailoring requirements to the context. Rapid assessments have been demonstrated to be relatively quick and inexpensive. ⁶⁹ Ethical frameworks, such as the principles and benchmarks proposed by Emanuel et al. ⁷⁰ could also assist in adapting processes. None of the studies included in this review stated using specific tools.

Limitations

Categorization in themes was based on studies’ objectives and did not consider findings, leading to a potential underrepresentation of themes. Researchers conducting this review are experienced in vaccine trials in Sub-Saharan Africa, but are not from the region, representing an external view that might have affected representation.

Although practices changed over time, we did not set up a time limit and the first study identified dated from 1997. Older studies had a greater focus on the adequacy of individual informed consent and applicability of international standards.

Conclusion

The review raised ethical concerns about respect of participants’ rights and validity of informed consent in vaccine trials in Sub-Saharan Africa. The emphasis on promoting understanding and free decision-making is crucial for vaccine trials enrolling healthy individuals that do not obtain any healthcare benefit from participating. These highlight the need for greater emphasis to the context and participants and communities’ needs. To address these, funders, sponsors and researchers should allocate adequate resources to design processes that are adapted, working together with community members and representatives and adding flexibility to modify these as necessary. ERBs should also support these processes. The focus should be moved from meeting recruitment targets to also consider metrics related to how these were achieved and how responsive these processes were to the context.