Participation in two phase II prophylactic HIV vaccine trials in the UK

Why do people take part in vaccine trials? A mixed methods narrative synthesis

OBJECTIVES

To understand why individuals do or do not take part in vaccine trials, exploring the motivators and barriers to identify effective strategies to optimise recruitment in vaccine research.

METHODS

Qualitative studies and quantitative surveys capturing data on reasons for trial participation/decline were included. Six databases were searched from 1996 to October 2021. Two reviewers independently screened and assessed risk of bias. Results were reported narratively and analysed using thematic analysis.

RESULTS

We included 32 studies (17 qualitative; 12 quantitative; 3 mixed-methods) that covered a wide range of populations, geographical areas and disease types. Eight themes were identified 1) altruism; 2) potential for personal benefit; 3) perceived risks; 4) trust or distrust; 5) social networks; 6) stigma; 7) practical implications; 8) research vanguard.

CONCLUSION

Our findings provide a detailed description of how potential participants weigh up their decisions to participate in vaccine trials, which could inform the planning and implementation of studies to enhance recruitment.

PRACTICE IMPLICATIONS

Clinical trial researchers should consider a patient-centered approach to recruitment, tailoring promoting material and attempt to understand fears, stigma and perceived risks. In addition, recognising the importance of trust and the key role friends, communities, family, and those in supervisory positions play in decisions.

Exceptional Risk: Healthy Volunteers' Perceptions of HIV/AIDS Clinical Trials

As with all early-stage testing of investigational drugs, clinical trials targeting HIV/AIDS can pose unknown risks to research subjects. Unlike sick participants seeking a therapeutic benefit, the motivations and barriers for healthy volunteers are more complex and understudied. Drawing on interviews and clinical trial data from 178 healthy volunteers, we examine how they perceive HIV/AIDS studies in the early stages of testing. A subset of healthy volunteers see phase I HIV/AIDS studies as particularly risky for reasons ranging from fear of catching the disease or having long-lasting and uncomfortable side effects to inexplicable fears that they cannot even articulate. Some participants have had past negative experiences in such trials that inform these views, but others cite information from staff and other participants as influential. Healthy volunteers' general fears concerning AIDS also shape their views of participating in phase I HIV/AIDS clinical trials.

Typologies of Altruistic and Financial Motivations for Research Participation

Questions arise concerning participants' motives in risky studies, such as HIV vaccine trials (HVTs). We interviewed in-depth 20 gay/bisexual men. Participants described both altruistic and nonaltruistic motives. Altruistic motivations emerged primarily, with nine typologies: (a) cultural, (b) community related, (c) familial, (d) religious, (e) professional, (f) political (e.g., HIV activism), (g) moral (e.g., making up for past wrongs), (h) existential (e.g., providing sense of meaning), and (i) other psychological (e.g., emotional gratification). Views of compensation varied: not a factor (55%), added incentive (25%), main motivator, but in conjunction with altruism (15%), and primary motivator (5%). HVT participants thus often have both altruistic and financial motives, and related typologies emerged. These findings have critical implications for studies on HIV, other conditions, and research ethics.

Accelerating clinical development of HIV vaccine strategies: methodological challenges and considerations in constructing an optimised multi-arm phase I/II trial design

Background

Many candidate vaccine strategies against human immunodeficiency virus (HIV) infection are under study, but their clinical development is lengthy and iterative. To accelerate HIV vaccine development optimised trial designs are needed. We propose a randomised multi-arm phase I/II design for early stage development of several vaccine strategies, aiming at rapidly discarding those that are unsafe or non-immunogenic.

Methods

We explored early stage designs to evaluate both the safety and the immunogenicity of four heterologous prime-boost HIV vaccine strategies in parallel. One of the vaccines used as a prime and boost in the different strategies (vaccine 1) has yet to be tested in humans, thus requiring a phase I safety evaluation. However, its toxicity risk is considered minimal based on data from similar vaccines. We newly adapted a randomised phase II trial by integrating an early safety decision rule, emulating that of a phase I study. We evaluated the operating characteristics of the proposed design in simulation studies with either a fixed-sample frequentist or a continuous Bayesian safety decision rule and projected timelines for the trial.

Results

We propose a randomised four-arm phase I/II design with two independent binary endpoints for safety and immunogenicity. Immunogenicity evaluation at trial end is based on a single-stage Fleming design per arm, comparing the observed proportion of responders in an immunogenicity screening assay to an unacceptably low proportion, without direct comparisons between arms. Randomisation limits heterogeneity in volunteer characteristics between arms. To avoid exposure of additional participants to an unsafe vaccine during the vaccine boost phase, an early safety decision rule is imposed on the arm starting with vaccine 1 injections. In simulations of the design with either decision rule, the risks of erroneous conclusions were controlled <15%. Flexibility in trial conduct is greater with the continuous Bayesian rule. A 12-month gain in timelines is expected by this optimised design. Other existing designs such as bivariate or seamless phase I/II designs did not offer a clear-cut alternative.

Conclusions

By combining phase I and phase II evaluations in a multi-arm trial, the proposed optimised design allows for accelerating early stage clinical development of HIV vaccine strategies.

Motivators to participation in actual HIV vaccine trials

An examination of actual HIV vaccine trials can contribute to an understanding of motivators for participation in these studies. Analysis of these motivators reveals that they can be categorized as social and personal benefits. Social benefits are generally altruistic, whereas personal benefits are psychological, physical, and financial. In this systematic review, the authors performed a literature search for actual preventive HIV vaccine trials reporting motivators to participation. Of studies conducted in the Organization for Economic Co-operation and Development (OECD) countries, the authors retrieved 12 studies reporting on social benefits and seven reporting on personal benefits. From the non-OECD countries, nine studies reported on social benefits and eight studies on personal benefits. Social benefits were most frequently described on macroscopic, altruistic levels. Personal benefits were most frequently psychological in nature. Rates of participation were compared between the OECD and the non-OECD countries. Knowledge of actual motivators in specific countries and regions can help target recruitment in various types of actual HIV vaccine trials.

Experiences on recruitment and retention of volunteers in the first HIV vaccine trial in Dar es Salam, Tanzania - the phase I/II HIVIS 03 trial

Background

Eventual control of HIV/AIDS is believed to be ultimately dependent on a safe, effective and affordable vaccine. Participation of sub-Saharan Africa in the conduct of HIV trials is crucial as this region still experiences high HIV incidences. We describe the experience of recruiting and retaining volunteers in the first HIV vaccine trial (HIVIS03) in Tanzania.

Methods

In this trial enrolled volunteers from amongst Police Officers (POs) in Dar es Salaam were primed with HIV-1 DNA vaccine at months 0, 1 and 3; and boosted with HIV-1 MVA vaccine at months 9 and 21. A stepwise education provision/sensitization approach was employed to eventual recruitment. Having identified a “core” group of POs keen on HIV prevention activities, those interested to participate in the vaccine trial were invited for a first screening session that comprised of provision of detailed study information and medical evaluation. In the second screening session results of the initial assessment were provided and those eligible were assessed for willingness to participate (WTP). Those willing were consented and eventually randomized into the trial having met the eligibility criteria. Voluntary participation was emphasized throughout.

Results

Out of 408 POs who formed the core group, 364 (89.0%) attended the educational sessions. 263 out of 364 (72.2%) indicated willingness to participate in the HIV vaccine trial. 98% of those indicating WTP attended the pre-screening workshops. 220 (85.0%) indicated willingness to undergo first screening and 177 POs attended for initial screenings, of whom 162 (91.5%) underwent both clinical and laboratory screenings. 119 volunteers (73.5%) were eligible for the study. 79 were randomized into the trial, while 19 did not turn up, the major reason being partner/family advice. 60 volunteers including 15 females were recruited during a one-year period. All participated in the planned progress updates workshops. Retention into the schedule was: 98% for the 3 DNA/placebo vaccinations, while it was 83% and 73% for the first and second MVA/placebo vaccinations respectively.

Conclusion

In this first HIV vaccine trial in Tanzania, we successfully recruited the volunteers and there was no significant loss to follow up. Close contact and updates on study progress facilitated the observed retention rates.

Trial registration numbers

ISRCTN90053831 ISRNCT01132976 and ATMR2009040001075080

Motivators to participation in medical trials: the application of social and personal categorization

The Health Belief Model provides a framework to understand motivators for volunteering for medical research. Motivators can take the form of social and personal benefits. In this systematic review of review articles, we contrast motivators of participation in actual cancer trials to those in actual HIV vaccine trials. We retrieved eight review articles from 2000 to 2012 examining motivators to participation in actual cancer trials. Personal benefits were most often psychological in nature, such as "coping with symptoms." Social benefits included "advancing research," "helping other cancer patients," and "for their family." While specific motivators vary between considerations - cancer research and HIV vaccine trials, these motivators fall into similar categories at similar frequencies. For example, personal/psychological benefits are common in each. Participant recruitment must be mindful of these categories of motivators for both cancer and HIV vaccine research.

Conceptual framework for behavioral and social science in HIV vaccine clinical research

HIV vaccine clinical research occurs within a context where biomedical science and social issues are interlinked. Previous HIV vaccine research has considered behavioral and social issues, but often treated them as independent of clinical research processes. Systematic attention to the intersection of behavioral and social issues within a defined clinical research framework is needed to address gaps, such as those related to participation in trials, completion of trials, and the overall research experience. Rigorous attention to these issues at project inception can inform trial design and conduct by matching research approaches to the context in which trials are to be conducted. Conducting behavioral and social sciences research concurrent with vaccine clinical research is important because it can help identify potential barriers to trial implementation, as well as ultimate acceptance and dissemination of trial results. We therefore propose a conceptual framework for behavioral and social science in HIV vaccine clinical research and use examples from the behavioral and social science literature to demonstrate how the model can facilitate identification of significant areas meriting additional exploration. Standardized use of the conceptual framework could improve HIV vaccine clinical research efficiency and relevance.