Barriers and motivations to volunteers' participation in preventive vaccine trials: a systematic review

Factors, motivations and barriers associated with eagerness to volunteer in COVID-19 vaccine clinical trials in France: A mixed-method study

INTRODUCTION

During the COVID-19 pandemic, there was an unprecedented effort to engage people in clinical vaccine research. Most of the French volunteers registered in the first weeks after the launch in October 2020 of COVIREIVAC, an electronic platform dedicated to COVID-19 vaccine clinical trials (VCT). In the context of pandemic preparedness, identifying factors associated with eagerness or hesitancy to participate in VCT may help to increase recruitment of volunteers from diverse backgrounds.

METHODS

We used a mixed-method survey offered to the volunteers registered on the COVIREIVAC platform, and semi-directed interviews in participants to COVID-19 VCTs. Volunteers were divided into three categories: early volunteers (EV), registered before the launch of the COVID-19 vaccination campaign, middle volunteers (MV) registered between the first of January 2021 and the generalization of the COVID-19 vaccination to the entire population in May 2021, and late volunteers (LV) registered afterward.

RESULTS

Among the 56,101 COVIREIVAC registered volunteers, 2,741 (4.9 %) completed the survey, 1,915 (69.6%) were EV, 301 (11.0%) were MV and 525 (19.2 %) were LV. Sixteen were face-to-face interviewed. Age, educational level, attitudes toward vaccination evaluated with the 5C-model did not differ between EV and MV. Women gender and the possibility to choose the vaccine platform was associated with being a MV. LV were significantly younger, had a lower educational level and had less positive attitudes toward vaccines than EV and MV. The main motivations for participation in VCTs were altruistic notably in EV and MV. For LV, they registered in the hope to choice the vaccine technology. Among the respondents, 2,041 (74.5 %) would consider to participate in a non-COVID-19 VCT.

CONCLUSION

LV on the COVIREIVAC platform had a distinct profile from EV and MV, and were less confident in vaccines. Restoring confidence in vaccines and clinical may help to engage more diverse populations in VCTs.

Vaccines and monoclonal antibodies to prevent healthcare-associated bacterial infections

SUMMARYHealthcare-associated infections (HAIs) represent a burden for public health with a high prevalence and high death rates associated with them. Pathogens with a high potential for antimicrobial resistance, such as ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and Clostridioides difficile, are responsible for most HAIs. Despite the implementation of infection prevention and control intervention, globally, HAIs prevalence is stable and they are mainly due to endogenous pathogens. It is undeniable that complementary to infection prevention and control measures, prophylactic approaches by active or passive immunization are needed. Specific groups at-risk (elderly people, chronic condition as immunocompromised) and also healthcare workers are key targets. Medical procedures and specific interventions are known to be at risk of HAIs, in addition to hospital environmental exposure. Vaccines or monoclonal antibodies can be seen as attractive preventive approaches for HAIs. In this review, we present an overview of the vaccines and monoclonal antibodies in clinical development for prevention of the major bacterial HAIs pathogens. Based on the current state of knowledge, we look at the challenges and future perspectives to improve prevention by these means.

Knowledge and Attitudes of Clinical Trials among Patients with Rare Diseases and the Guardians in China

BACKGROUND

Conducting of clinical trials for rare diseases faces multiple challenges. Patients' cognition and attitude toward clinical trials are crucial, which may affect their participation and compliance, and affect the schedule of clinical trials eventually.

OBJECTIVE AND METHOD

This study aims to explore the knowledge and attitudes of clinical trials of patients with rare diseases or patients' guardians. An anonymous cross-sectional survey was conducted from November 1, 2021, to November 30, 2021. A total of 1131 valid questionnaires were included. Among them, 417 were filled in by the patients themselves, and 714 were answered by the patients' guardians.

RESULTS

The average score of clinical trial knowledge of the patients (8.25) was lower than that of the guardians (8.85). The willingness of the patients to participate in clinical trials was high (4.28), and the willingness of the patients' guardians was also high for patients to participate in clinical trials (4.35). The main promoting factors of clinical trial participation were the possibility of curing the disease. The main hindering factors of participation in clinical trials were lack of access to clinical trial information and concern about the safety and effectiveness of the trial drug.

CONCLUSIONS

In conclusion, most respondents had some basic knowledge of clinical trials and high willingness to participate in clinical trials. But there were some cognitive deficiencies about clinical trials and many hindering factors to participate in clinical trials. Clinical trials of rare diseases should be patient-centered and truly meet the unmet clinical, psychological, and social needs of patients with rare diseases.

Factors that impact on recruitment to vaccine trials in the context of a pandemic or epidemic: a qualitative evidence synthesis

BACKGROUND

The World Health Organization declared the COVID-19 pandemic on 11 March 2020. Vaccine development and deployment were swiftly prioritised as a method to manage and control disease spread. The development of an effective vaccine relies on people's participation in randomised trials. Recruitment to vaccine trials is particularly challenging as it involves healthy volunteers who may have concerns around the potential risks and benefits associated with rapidly developed vaccines.

OBJECTIVES

To explore the factors that influence a person's decision to participate in a vaccine trial in the context of a pandemic or epidemic.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was June 2021.

SELECTION CRITERIA

We included qualitative studies and mixed-methods studies with an identifiable qualitative component. We included studies that explored the perspectives of adults aged 18 years or older who were invited to take part in vaccine trials in the context of a pandemic or epidemic.

DATA COLLECTION AND ANALYSIS

We assessed the title, abstracts and full texts identified by the search. We used a sampling frame to identify data-rich studies that represented a range of diseases and geographical spread. We used QSR NVivo to manage extracted data. We assessed methodological limitations using an adapted version of the Critical Skills Appraisal Programme (CASP) tool for qualitative studies. We used the 'best-fit framework approach' to analyse and synthesise the evidence from our included studies. We then used the Confidence in the Evidence from Reviews of Qualitative research (GRADE-CERQual) assessment to assess our confidence in each finding and develop implications for practice.

MAIN RESULTS

We included 34 studies in our review. Most studies related to HIV vaccine trials. The other studies related to Ebola virus, tuberculosis, Zika virus and COVID-19. We developed 20 key findings, under three broad themes (with seven subthemes), that described the factors that people consider when deciding whether to take part in a vaccine trial for a pandemic or epidemic disease. Our GRADE-CERQual confidence was high in nine of the key findings, moderate in 10 key findings and low in one key finding. The main reason for downgrading review findings were concerns regarding the relevance and adequacy of the underlying data. As a result of the over-representation of HIV studies, our GRADE-CERQual assessment of some findings was downgraded in terms of relevance because the views described may not reflect those of people regarding vaccine trials for other pandemic or epidemic diseases. Adequacy relates to the degree of richness and quantity of data supporting a review finding. Moderate concerns about adequacy resulted in a downgrading of some review findings. Some factors were considered to be under the control of the trial team. These included how trial information was communicated and the inclusion of people in the community to help with trial information dissemination. Aspects of trial design were also considered under control of the trial team and included convenience of participation, provision of financial incentives and access to additional support services for those taking part in the trial. Other factors influencing people's decision to take part could be personal, from family, friends or wider society. From a personal perceptive, people had concerns about vaccine side effects, vaccine efficacy and possible impact on their daily lives (carer responsibilities, work, etc.). People were also influenced by their families, and the impact participation may have on relationships. The fear of stigma from society influenced the decision to take part. Also, from a societal perspective, the level of trust in governments' involvement in research and trial may influence a person's decision. Finally, the perceived rewards, both personal and societal, were influencing factors on the decision to participate. Personal rewards included access to a vaccine, improved health and improved disease knowledge, and a return to normality in the context of a pandemic or epidemic. Potential societal rewards included helping the community and contributing to science, often motivated by the memories of family and friends who had died from the disease.

AUTHORS' CONCLUSIONS

This review identifies many of the factors that influence a person's decision to take part in a vaccine trial, and these reflect findings from reviews that examine trials more broadly. However, we also recognise some factors that become more important in connection with a vaccine trial in the context of a pandemic or epidemic. These factors include the potential stigma of taking part, the possible adverse effects of a vaccine, the added motivation for helping society, the role of community leaders in trial dissemination, and the level of trust placed in governments and companies developing vaccines. These specific influences need to be considered by trial teams when designing, and communicating about, vaccine trials in the context of a pandemic or epidemic.

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.

Intention to participate in COVID-19 vaccine clinical trials in May 2021: a cross-sectional survey in the general French population

In May 2021, while the immunization campaign was in progress, the emergence of new SARS-CoV-2 variants led us to assess attitudes toward participation in a COVID-19 vaccine clinical trial (VCT) in France. Between the 10th and the 23rd of May 2021, we conducted a cross-sectional online survey among a representative sample of the French population aged 18 and over and a specific sample of the French population over 65. Among the 3,056 respondents, 28.0% (856) would consider participation in a COVID-19 VCT. Factors independently negatively associated with willingness to participate in a COVID-19 VCT were female gender with an adjusted odd ratio (aOR) 0.42 and 95% confidence interval (95% CI) 0.35–0.51, and mistrust in health actors (in their own physician and pharmacists, health ministry, government, scientists in medias, medias and pharmaceutical companies) with aOR 0.86 (95% CI 0.84–0.88) by one-point increase in mistrust in health actors score. Factors positively associated with willingness to participate in a COVID-19 VCT were COVID-19 vaccination or intention to get vaccinated with aOR 4.89 (95% CI 3.15–7.61), being a healthcare worker with aOR 2.051 (95% CI 1.51–2.80), being at risk for severe COVID-19 with aOR 1.39 (95% CI 1.14–1.69) and altruism as the main reason for getting vaccination with aOR 1.56 (95% CI 1.29–1.88). In May 2021, despite COVID 19 vaccine availability, 28% of the French population would agree to participate in a COVID-19 VCT. Mistrust in health actors contributes to a reduction in the intention to participate. Attitudes toward COVID-19 vaccination predict attitudes toward participation in a COVID-19 VCT.

Factors that impact on recruitment to vaccine trials during a pandemic or epidemic: a qualitative evidence synthesis

This is a protocol for a Cochrane Review (qualitative). The objectives are as follows:

This is a protocol for a Cochrane Review (qualitative). The review aims to explore the factors associated with a person’s decision to take part in a pandemic or epidemic vaccine trial.

Characterization of Individuals Interested in Participating in a Phase I SARS-CoV-2 Vaccine Trial

The development of an effective vaccine against SARS-CoV-2 marks one of the highest priorities during the ongoing pandemic. However, recruitment of participants for clinical trials can be challenging, and recruitment failure is among the most common reasons for discontinuation in clinical trials. From 20 May 2020, public announcements about a planned phase I trial of the vaccine candidate MVA-SARS-2-S against SARS-CoV-2 began, and interested individuals started contacting the study team via designated e-mail. All emails received from these individuals between 20 May 2020–30 September 2020 were assessed. Of the 2541 interested volunteers, 62% contacted the study team within three days after the first media announcement. The average age was 61 years (range 16–100), 48% of volunteers were female and 52% male. A total of 274, 186, and 53 individuals, respectively, reported medical pre-conditions, were health-care workers, or had frequent inter-person contacts. In conclusion, we report a high number of volunteers, with a considerable percentage stating factors for an elevated risk to acquire COVID-19 or develop severe disease. Factors such as media coverage and the perception of a disease as an acute threat may influence the individual’s choice to volunteer for a vaccine trial. Our data provide first important insights to better understand reasons to participate in such trials to facilitate trial implementation and recruitment.

Barriers and facilitators to the participation of subjects in clinical trials: An overview of reviews

BACKGROUND

The demand for clinical trial participants is today one of the highest it has ever been and continues to increase. At the same time, subject recruitment continues to be problematic and the major reason for clinical trial premature terminations. The literature on clinical trial recruitment, which spans several decades and includes hundreds of studies, has an abundance of findings that can be synthesized by way of an overview to provide a well-informed and complete picture of the factors that determine subject participation.

OBJECTIVES

An overview of the systematic reviews that report barriers and facilitators to clinical trial participation was conducted. The extracted data were synthesized, and a thematic framework of the factors that affect subject participation in clinical trials was developed. The overview extended across medical subjects and demographics.

METHODS

Thirty reviews that complied with the inclusion criteria were included. These reviews covered 753 relevant primary studies and reported 881 barriers and facilitators. The barriers and facilitators were thematically synthesized and a thematic framework of 20 themes was developed. The quality of the included reviews was assessed and reported.

MAIN RESULTS

Several opportunities to increase clinical trial participation, by developing interventions and changing the trial design, derived from an analysis of the thematic framework. That analysis also showed that most of the 20 themes operate mainly as a barrier or as a facilitator, and that most have an effect across medical subjects. As to the quality elements assessed, some reviews complied almost fully but most only partially.

Assessing Knowledge of HIV Vaccines and Biomedical Prevention Methods Among Transgender Women in the New York City Tri-State Area

Purpose: To lower the HIV risk of transgender women, it is imperative to understand their unique HIV prevention needs and design biomedical prevention interventions that are responsive to the psychosocial, behavioral, and clinical needs of these communities. Preventive HIV vaccines are an important modality under investigation in diverse study participants. We sought to assess the knowledge of HIV vaccine research and the most common barriers and facilitators to participation in HIV vaccine studies among HIV-negative transgender women living in New York City.

Methods: Six focus groups were conducted among 29 participants recruited in the New York City tri-state area from December 2014 to July 2015. Prefocus group quantitative questionnaire assessed demographic, behavioral information, knowledge of preventive vaccine research, and reasons for potential participation in prevention studies.

Results: Median age of participants was 29 years and 41.4% identified as white. Over half of participants have heard of preventive vaccine research and majority indicated that an important factor in participating in HIV prevention research is to help the community collective effort. Key barriers that emerged were fear of side effects, feelings of exclusion from biomedical research. Facilitators to participation in prevention studies included trusting relationships with providers.

Conclusions: These barriers and facilitators are important to consider in the design of studies inclusive of trans communities and transgender-specific prevention strategies. Barriers may be overcome by disseminating accurate information via social media or health providers.

Barriers and motivations for participation in preventive vaccine clinical trials: Experience of 5 clinical research sites

Recruitment in preventive vaccine trials (PVT) is challenging due to common barriers to clinical research and lack of vaccine confidence. Identifying determinants of participation can help to improve recruitment. A prospective survey was conducted in 5 French clinical investigational sites. People asked to participate in a PVT were given a questionnaire whether they decided to participate or not in the trial. A total of 341 people answered the survey: 210 accepting and 131 declining to participate in a PVT. Acceptors were significantly younger (38.5 vs 54.9 years old), more likely to be involved in early phase trials, had a higher level of education (p < 0.005) and a significantly better general opinion concerning vaccines (92.3% versus 72.3%, p < 0.005) compared with those who declined. Factors associated with acceptance or refusal were evaluated in 224 people in the 4 sites where both groups were included. In a multivariate analysis, three factors: older age, having heard about PVT through multiple sources and financial incentives were significantly associated with refusal to participate in the PVT. A generally favourable opinion of vaccines was associated with acceptance. The main motivation for participation was altruism (93.2%) whereas fear of side effects was at the forefront of the barriers (36.6%). Information given by the physician was a key point for decision-making in 70.2% of those who accepted. In brief, vaccine hesitancy may decrease recruitment in PVTs; reinforcing altruism and quality of information given are key points in acceptance of participation in PVT.

Predictors of Participation in a Nonpharmacological Intervention for Chronic Back Pain

Objective

Cognitive behavioral therapy for chronic pain (CBT-CP) has been identified as an evidence-based adjunct or alternative to opioid pain care. However, little is known about which patients participate in CBT-CP. This study examined predictors of enrollment in a noninferiority trial of in-person vs technology-based CBT-CP for patients with chronic back pain.

Setting

A single Veterans Health Affairs (VHA) medical center.

Subjects

Veterans with chronic back pain.

Design and Methods

For eligible participants (N = 290), individual factors (demographics, distance from a VHA medical center, pain intensity, receipt of opioid prescription, and recruitment method) collected at trial screening were examined to identify predictors of enrollment (i.e., signed consent form). Of those who enrolled, duration of participation in the treatment portion of the study was examined.

Results

Among eligible patients, 54% declined enrollment due to lack of interest. Regression analyses revealed that patients not in receipt of an opioid were more likely to enroll. The probability of being in the trial long enough to receive a "dose" of treatment (3 visits or more) was 0.76 (0.04).

Conclusions

Overall, enrollment rates were low. However, most patients who enrolled in the study (102 of 134 signed consent) were retained and received a treatment dose. Patients not receiving opioids were more likely to enroll, suggesting that patients who are prescribed opioids, an important group for treatment outreach, are likely underengaged. Identifying predictors of enrollment in CBT-CP may help increase recruitment efficiency and assist in targeting patients who may benefit but are not currently interested in treatment.

Evaluating recruitment strategies for AUSPICE, a large Australian community-based randomised controlled trial

OBJECTIVES

To examine the effectiveness of different strategies for recruiting participants for a large Australian randomised controlled trial (RCT), the Australian Study for the Prevention through Immunisation of Cardiovascular Events (AUSPICE).

DESIGN, SETTING, PARTICIPANTS

Men and women aged 55-60 years with at least two cardiovascular risk factors (hypertension, hypercholesterolaemia, overweight/obesity) were recruited for a multicentre placebo-controlled RCT assessing the effectiveness of 23-valent pneumococcal polysaccharide vaccine (23vPPV) for preventing cardiovascular events.

METHODS

Invitations were mailed by the Australian Department of Human Services to people in the Medicare database aged 55-60 years; reminders were sent 2 weeks later. Invitees could respond in hard copy or electronically. Direct recruitment was supplemented by asking invitees to extend the invitation to friends and family (snowball sampling) and by Facebook advertising.

MAIN OUTCOME

Proportions of invitees completing screening questionnaire and recruited for participation in the RCT.

RESULTS

21 526 of 154 992 invited people (14%) responded by completing the screening questionnaire, of whom 4725 people were eligible and recruited for the study. Despite the minimal study burden (one questionnaire, one clinic visit), the overall participation rate was 3%, or an estimated 10% of eligible persons. Only 16% of eventual participants had responded within 2 weeks of the initial invitation letter (early responders); early and late responders did not differ in their demographic or medical characteristics. Socio-economic disadvantage did not markedly influence response rates. Facebook advertising and snowball sampling did not increase recruitment.

CONCLUSIONS

Trial participation rates are low, and multiple concurrent methods are needed to maximise recruitment. Social media strategies may not be successful in older age groups.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12615000536561.

Willingness to Participate and Associated Factors in a Zika Vaccine Trial in Indonesia: A Cross-Sectional Study

One of the crucial steps during trials for Zika and other vaccines is to recruit participants and to understand how participants' attitudes and sociodemographic characteristics affect willingness to participate (WTP). This study was conducted to assess WTP, its explanatory variables, and the impact of financial compensation on WTP in Indonesia. A health facility-based cross-sectional study was conducted in eleven regencies in the Aceh and West Sumatra provinces of Indonesia. Participants were recruited via a convenience sampling method and were interviewed. The associations between explanatory variables and WTP were assessed using a two-step logistic regression analysis. A total of 1,102 parents were approached, and of these 956 (86.8%) completed the interview and were included in analysis. Of those, 144 (15.1%) were willing to participate in a Zika vaccine trial without a financial compensation. In the multivariate analysis, WTP was tied to an age of more than 50 years old, compared to 20⁻29 years (odds ratio (OR): 5.0; 95% confidence interval (CI): 2.37⁻10.53), to being female (OR: 2.20; 95% CI: 1.11⁻4.37), and to having heard about Zika (OR: 2.41; 95% CI: 1.59⁻3.65). Participants' WTP increased gradually with higher financial compensation. The rate of WTP increased to 62.3% at the highest offer (US$ 350.4), and those who were still unwilling to participate (37.7%) had a poorer attitude towards childhood vaccination. This study highlights that pre-existing knowledge about Zika and attitudes towards childhood vaccination are important in determining community members being willing to participate in a vaccine trial. Financial incentives are still an important factor to enhance participant recruitment during a vaccine trial.

Recruitment barriers for prophylactic vaccine trials: A study in Belgium

Recruitment of volunteers is one of the main challenges in clinical trial management, and there is little information about recruitment barriers for preventative vaccine trials. We investigated both the recruitment barriers and recruitment strategies for preventive vaccine trials in Belgium. A 10 min survey was used as well as interviews of staff at all clinical trial sites in Belgium that regularly perform vaccine trials. We observed that there are successful recruitment strategies and few recruitment issues for trials involving healthy adults and those over 65 years old. However, challenges face the recruitment of paediatric populations, pregnant women, patients and the very elderly (over 85 years old). From these results, we identified three priority areas to increase recruitment for prophylactic vaccine trials in Belgium. These are: the lack of public knowledge about infectious diseases; the lack of resources of healthcare professionals to take part in clinical trials; and the burden to potential volunteers to take part in a trial. These were discussed with stakeholders and solutions were proposed.