RBDCOV HIPRA-HH-4 Clinical Trial | Results Report: Participants’ Experience Assessment Study

PENDING EUROPEAN COMMISSION APPROVAL

This results report presents the key findings from the psychosocial study conducted alongside the HIPRA-HH-4 vaccine clinical trial, part of the RBDCOV project. Coordinated by the European AIDS Treatment Group (EATG), the research explored how people living with immunocompromising conditions, such as HIV, autoimmune diseases, or kidney diseases, experienced taking part in a COVID-19 vaccine study.

Through surveys and in-depth interviews, participants shared what motivated them to join, what concerns they carried, and how they felt about communication, trust, inclusion, and support throughout the trial. The findings reveal high levels of satisfaction, alongside valuable lessons on how to improve participant engagement, feedback, and equity in future clinical research.

The report offers rich, evidence-based insights for researchers, sponsors, ethics committees, and community organisations committed to making clinical trials more inclusive and people-centred.

The report is available now in English, Spanish, Catalan and Turkish.

Download and read the report

Executive Summary

This report presents the findings of a psychosocial study conducted alongside the HIPRA-HH-4 clinical trial, which evaluated a COVID-19 vaccine specifically designed for people with immunocompromising conditions. The psychosocial component aimed to explore participants’ perspectives, motivations, expectations, and experiences before, during, and after their involvement in the trial. The study focused on understanding not only logistical and informational aspects but also the emotional and relational dynamics that shaped the experience.

A mixed-methods approach was used to generate comprehensive insights. A total of 54 participants completed an ad hoc online questionnaire, and 15 took part in semi-structured interviews. This combination allowed identifying key trends while also capturing the lived experiences and subjective perceptions of individuals with chronic or complex health conditions.

The results reveal high levels of satisfaction and trust, with participants describing the trial as well-organised, participant-centred, and meaningful. The professionalism of medical and research staff, clarity of communication, and perceived personal and social relevance of the study all contributed to positive evaluations. Many participants reported feeling recognised and valued, contributing to a strong sense of legitimacy and emotional engagement.

However, participants also identified areas for improvement, including:

• The need for post-trial feedback and results sharing, as many expressed a desire for closure and recognition.
• The absence of community-based recruitment channels limited outreach and inclusivity.
• The physical and logistical burden of procedures, particularly for those with limited mobility or multiple comorbidities.

Crucially, participants valued the specific focus on immunocompromised populations, often noting that they are excluded from research. The relevance of the study population reinforced trust, a sense of belonging, and motivation to participate.

Overall, the findings provide practical and ethical insights to inform the design of future clinical studies, especially those targeting medically and socially vulnerable populations. Placing participants’ voices at the centre of the research process can significantly enhance recruitment, retention, and long-term engagement in research.

Key Insights

Respectful treatment and meaningful support

Participants consistently reported a high level of respect and emotional support throughout their participation in the HIPRA-HH-4 trial. Their experience in the clincial trial was positive and marked by respectful treatment.

In the survey, 92.6% totally agreed that they were treated with respect by both the research staff and hospital personnel, such as nurses and technicians. In addition, 77.8% totally agreed that they felt supported throughout the process.

“I felt very well looked after. They knew what they were doing.”

“They treated me very well. I was never left with any unanswered questions.”

Participants emphasised that respect and attentiveness were not peripheral aspects of their experience, they were central to fostering trust and engagement. In future trials, relational quality must continue to be considered a core ethical and scientific component.

Motivations to participate: contribution to science and self-protection

Participants’ motivations for joining the trial were shaped by a combination of personal protection and civic engagement. Among the possible reasons, 66.7% rated very important: “To contribute to COVID-19 research on people with my condition”, the most strongly endorsed item in the entire survey; 66.7% rated very important “To be better protected from severe COVID-19 infection and its consequences”; and 53.7% rated very important: “To support research and science in general”.

“I have a chronic illness and thought it would be good to access this kind of vaccine.”

“Everything we have today is thanks to others who participated before us. Now it’s our turn to help those who come after.”

Among participants living with HIV, the motivation to support scientific research was particularly strong, suggesting a dual commitment to both personal protection and community contribution, possibly shaped by previous experiences with participatory research and collective advocacy.

Recruitment and communication strategies should continue to integrate both individual and civic motivations, both dimensions are powerful and intertwined.

Relational trust compensated for scientific uncertainty

Operational clarity was strong, but conceptual understanding of the trial’s scientific rationale was more fragile. While 81.5% os respondent totally agreed they felt comfortable asking questions before, during, and after joining the trial, qualitative insights revealed gaps:

“I thought it was just another dose like the previous ones.”

“There were things I didn’t fully understand, but I felt well supported.”

This dynamic, where trust in healthcare providers substitutes for scientific understanding, must be addressed. Relational trust is necessary but not sufficient; future trials should reinforce iterative and tailored communication to enhance conceptual understanding.

Gender, age and experience shaped satisfaction

Differences in participant satisfaction emerged by prior clinical trial experience, gender, and age:

• Women: 75% very satisfied; 25% satisfied.
• Men: 61.3% very satisfied; 29% satisfied; 9.7% neutral.
• Participants aged 56–70 reported the highest satisfaction (65.2% very satisfied), with slightly more variability at the youngest and oldest ends of the spectrum.
• First-time participants: 64.7% very satisfied, 29.4% satisfied.
• Experienced participants: 50% very satisfied, 50% satisfied.

“It was my first time, so I was curious and a little nervous. But it was a good surprise.”

“I had already participated in other trials. I knew what to expect.”

These findings highlight the need to tailor communication and engagement strategies to participants’ prior experience, gender, and life stage.

The procedural burden was acceptable but visible

Overall, participants accepted the logistical demands of the trial, but minor physical and organisational burdens were reported, particularly blood sampling and fatigue related to visits:

“In two of the extractions it was difficult to find the right vein, and I felt uncomfortable due to the hematomas.”

“Fifteen tubes per visit was a bit much, but in the end, it was worth it.”

“The trial went well, but there were days when I ended up very tired. The visits were long.”

These concerns were not barriers to participation but highlight that even well-designed trials should explicitly address and minimise participant burden, particularly in fragile populations.

Feedback and closure: an unmet expectation

Many participants expressed a strong wish to receive individual or general feedback about the study outcomes:

“I would like a report to know how and to what extent the vaccine helped me.”

“As of today, I haven’t received any information about the trial results.”

This was the single most recurrent theme in open comments and interviews regarding potential improvements. Future trials must treat feedback as a core element of ethical reciprocity; not an optional courtesy.

Recruitment was too medically driven

While medical recruitment was efficient, future trials must diversify outreach strategies to ensure broader inclusion, especially for individuals with less regular healthcare access: 91% of participants heard about the trial through their physician.

“I found out through my doctor. I didn’t see it advertised anywhere.”

“There should be more ways for people to learn about these things.”

Inclusion of immunocompromised populations was deeply valued

Participants strongly appreciated being included in a trial designed for people like them, a group often excluded from research:

“Normally, I can’t participate in anything — they always leave us out.”

“For once, they thought of us, of the immunocompromised.”

“They always do studies in healthy people, not in people like us.”

“I thought: at least this time my situation counts for something.”

“I felt included because of my condition — they normally don’t call us for this.”

“I felt that my condition mattered in the research.”

“It’s not the same to get COVID if you are immunocompromised.”

Designing trials that explicitly include underrepresented populations increases both ethical legitimacy and emotional engagement.

Communication about compensation could be strengthened

Among participants, 72.2% totally agreed they clearly understood what they would be reimbursed for. Besides, 59.3% totally agreed that the amount received was satisfactory (Q37), but 13% were neutral and 3.8% expressed dissatisfaction.

“Since I received compensation, I moved up a tax bracket and had to pay taxes.”

While the compensation model was largely effective, transparency about possible administrative consequences and more personalised communication could further strengthen trust.

Clinical trial participation fostered emotional legitimacy and pride

Participants consistently described their experience not only in procedural terms, but also as a source of emotional legitimacy and personal meaning:

“I felt useful. As if I was contributing something.”

“I believe that through this I was able to help in some way.”

“I am satisfied, I would participate again in another study if they offered it.”

Feeling respected, included, and valued was as important as scientific understanding or logistical organisation. Future trials should explicitly recognise and cultivate this emotional and social dimension.

About the RBDCOV Project 

The RBDCOV project, which aimed to test a vaccine against COVID-19 in the pediatric population, including adolescents, and in immunocompromised individuals, plays a crucial role in vaccine development. 

RBDCOV is one of the projects committed to testing and advancing a new vaccine against COVID-19. For this purpose, companies and institutions from five European countries have joined forces. The project is led by the biotechnological pharmaceutical company HIPRA and involves the participation of centers in Spain (Vall d’Hebron Institut de Recerca, Irsicaixa, Fundación Lucha contra el SIDA (FLS), IDIBAPS, IDIBGI, ASPHALION, Vinces Consulting, Zabala Innovation), the United Kingdom (Veristat International), Italy (Fondazione Penta), Germany/Belgum (European AIDS Treatment Group), and Turkey (Metpharm Arastirma Gelistirme Saglik Danismanlik). 

Learn more about RBDCOV

The RBDCOV project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101046118. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.