Hypothetical HIV Vaccine Trial Research Articles

What motivates or demotivates intravenous drug users to participate in hypothetical HIV vaccine efficacy trial? A qualitative study from urban Tanzania

Background:HIV vaccine efficacy trials require the active participation of volunteers who are committed and adherent to the study protocol. However, information about the influence of Injecting Drug Users (IDUs) to participate in HIV vaccine efficacy trials in low-income countries is inadequate. The present study explored the factors that motivate or hinder IDUs from participating in HIV vaccine efficacy trials in Dar es Salaam, Tanzania.Methods:A qualitative descriptive study design was employed among IDUs at Muhimbili National Hospital (MNH). A purposeful sampling technique was used to recruit the participants. Three (3) focus group discussions (FGDs) and 10 In-Depth Interviews (IDIs) were used to collect the data. The data from participants were audio-recorded, transcribed, and analysed using the content analysis approach.Findings:The participants reported that altruism and the desire to reduce risks of HIV infection were the motivators to participate in hypothetical HIV vaccine trials. In addition, participants reported to consult close relatives towards motivation to participate in the vaccine trial. In contrast, the perceived fear of vaccine side effects, lack of information about HIV vaccine studies, and HIV-related stigma towards participants were described as barriers to participate in the HIV vaccine trials.Conclusion:Participation in a hypothetical HIV vaccine trial among IDUs is influenced by positive and negative factors. Actual recruitment plans could be made through a better explanation of HIV vaccine trials, the expected individual and collective benefits associated with the trials. Community involvement and sensitisation is likely to enhance participation in future HIV vaccine trials in Tanzania.

Willingness of female sex workers in Kampala, Uganda to participate in future HIV vaccine trials: a case control study

BackgroundWe anticipate large efficacy trials of novel HIV vaccines that have shown acceptable safety profiles. We determined willingness to participate (WTP) in future HIV vaccine efficacy trials among HIV negative female sex workers (FSWs) in Kampala Uganda.MethodsWe conducted a case control study in the Good Health for Women Project cohort. Cases received HIV prevention services and, enrolled in a 12-month simulated vaccine efficacy trial (SiVET) that used Hepatitis B vaccine; they underwent vaccine trial procedures as would be in an actual trial. Controls received similar health services but did not enroll in SiVET. We matched cases and controls (ratio 2:1) for age and duration in the cohort. We described a hypothetical HIV vaccine trial to cases (after 9 months in SiVET) and controls including trial attributes: randomization, delaying pregnancy, frequent blood draws (80-100mls) and study visits for 3 years. We compared WTP and willingness for vaccine trial attributes by case/control using chi-squared or Fisher’s exact tests and fitted conditional logistic regression models to determine independent predictors of WTP.ResultsWe analyzed data for 311 volunteers (219 cases, 92 controls); median age 27 years (IQR: 23–32), 39.9% had ≥secondary education, 57.9% had sex work as their main job and 81.9% used illicit drugs. Compared to controls, more cases had lived in the community for > 1 year, (85.4% vs 64.1%; p < 0.001) and fewer cases reported illicit drug use in the past 3 months, (79.0% vs 89.1%; p = 0.03). Overall, 278 (89.4%) volunteers expressed WTP in an HIV vaccine trial, the most common reason being hope of protection against HIV. More cases than controls (58.2% vs 44.7%) did not need to consult anyone before trial participation (p = 0.03); cases were more willing to delay pregnancy (99.0% vs 94.0%; p = 0.03). Combining vaccine trial attributes, 249 (89.6%) of the 278 accepted all attributes. After controlling for case/ control status women with secondary education or higher expressed less WTP (aOR 0.17; 95% CI 0.04–0.80).ConclusionFSWs in Kampala demonstrated high WTP. Prior experience with trial requirements like contraception may improve their uptake during actual trials. Family involvement is important for those without prior trial experience.

Willingness to Participate in Hypothetical HIV Vaccine Trial and Associated Factors among People Who Inject Drugs in Dar es Salaam, Tanzania.

This study is aimed at assessing the willingness to participate in the HIV vaccine trials and the associated factors among people who inject drugs (PWIDs) in Tanzania. Information about the willingness to participate and the associated factors was collected using interviewer-administered questionnaires at the medication treatment for opioid use disorder (MOUD) clinic in Dar es Salaam. Data analysis was performed using the IBM SPSS Statistic 20. The mean age of respondents was 36.7, and the standard deviation (SD) was ±7.2. The majority of respondents (68%) had primary education, and a high proportion of them were single (61.5%). More than one-third (37.9%) shared needles and syringes. Most (87.3%) had more than three sexual partners, and almost half (51.4%) did not use condoms during sexual intercourse with nonregular partners. About 63% had knowledge of HIV transmission while 27% had heard about HIV vaccine trials. Generally, 76% of the respondents expressed willingness to participate in future HIV vaccine trials regardless of prior knowledge of HIV vaccine trials. Willingness to participate in HIV vaccine trials was not associated with education level, people living with, knowledge about HIV transmission, awareness of HIV vaccine trials, sharing of syringe/needles, and number of sexual partners. Only older age (OR = 1.6, 95%CI = 1.01, 2.6) and condom use (OR = 0.49, 95%CI = 0.26, 0.97) showed an association with willingness. However, after performing logistic regression with factors at p value ≤ 0.2 to ascertain the other factors on the effects of age, condom use, education level, and sharing of needles/syringes, the results were not statistically significant. Although participants reported a high willingness to participate in hypothetical HIV vaccine trials, no definitive conclusion can be drawn about the associated factors. Further studies with intensive educational programs are needed to investigate the factors on willingness to participate in actual HIV vaccine trials among PWIDs.

Factors influencing mothers' decision to enroll their HIV-negative children in a hypothetical HIV vaccine trial.

This study explored the factors influencing mothers' decision-making about enrolling their HIV negative infants in a hypothetical HIV vaccine trial. Methods: HIV infected and uninfected mothers (n = 22) were interviewed. Several factors were identified as influencing the mothers' decisions, including perceptions and knowledge of HIV and vaccines. Maternal concerns about protecting their infants from HIV were also identified and mothers indicated that they were eager to vaccinate their children. Insufficient information and reassurance regarding vaccine trial safety and efficacy influenced maternal reluctance to enroll their child.

Age and sex or gender (sex/gender) and HIV vaccine preparedness

An examination of age and sex or gender (sex/gender) in HIV vaccine preparedness studies can contribute to an understanding of these demographic variables in preparation for actual HIV vaccine trials. In this descriptive review, age and sex or gender (sex/gender) were examined in relation to willingness to participate (WTP) and retention in an HIV vaccine trial. Twenty-five articles were retrieved from the Organization for Economic Co-operation and Development (OECD) countries and 28 articles were retrieved from the non-OECD countries. In US studies that involved mainly white MSM, older men were more likely to be WTP in a hypothetical HIV vaccine trial and more likely to be retained than younger men. In most OECD studies, sex/gender was not associated with WTP in a hypothetical HIV vaccine trial, while females were more likely to be retained in most studies. Largely, age was not associated with WTP in the non-OECD countries, but the results on sex/gender were more variable. The relationship between adolescent or adult WTP in hypothetical HIV vaccine trials in South Africa did not appear to be modified by high school student status. In addition, more studies in discordant couples in the context of HIV vaccine preparedness could be conducted to examine gender roles and inequalities in preparation for HIV vaccine trials.

Development and evaluation of a web-based assent for adolescents considering an HIV vaccine trial

HIV vaccine trials with minors will likely require parental permission and informed assent from adolescents. For this to be a valid process, the information needs to be presented in a manner that promotes adolescent comprehension. Previous studies suggest that adolescent comprehension of assent is often insufficient. We developed an interactive web-based assent that included interspersed quiz questions for a hypothetical HIV vaccine trial. Efficacy of the web-based assent was compared to a standard paper assent with and without interspersed questions. One hundred twenty teen participants, ages 15–17 years, from five community organizations were randomized to self-administered web-based assent (n = 60) or investigator-administered paper assent with (n = 29) or without (n = 31) interspersed quiz questions. After reviewing the assent, participants completed a 27-item comprehension test. Comprehension scores were compared between groups. The mean number of correctly answered questions were 21.2 for the full paper group and 21.1 for the web-based group (t118 = –0.08, p = 0.94). Scores were 20.2 for the paper without interspersed questions sub-group and 22.1 for the paper with interspersed questions sub-group (t58 = 1.96, p = 0.055). Participants in the web-based group performed as well on the comprehension test as those in the paper group, and those in the paper with questions sub-group performed better than those in the paper without questions sub-group, suggesting that interspersed quiz questions may improve understanding of a traditional paper assent. The minimal investigator time and standardized administration of the web-based assent as well as ability to tailor the assent discussion to topics identified by incorrect comprehension test responses are advantages worthy of further investigation.

Adolescent decision making about participation in a hypothetical HIV vaccine trial

PurposeThe purpose of this study was to examine the process of adolescent decision-making about participation in an HIV vaccine clinical trial, comparing it to adult models of informed consent with attention to developmental differences. MethodsAs part of a larger study of preventive misconception in adolescent HIV vaccine trials, we interviewed 33 male and female 16–19-year-olds who have sex with men. Participants underwent a simulated HIV vaccine trial consent process, and then completed a semistructured interview about their decision making process when deciding whether or not to enroll in and HIV vaccine trial. An ethnographic content analysis approach was utilized. ResultsTwelve concepts related to adolescents’ decision-making about participation in an HIV vaccine trial were identified and mapped onto Appelbaum and Grisso's four components of decision making capacity including understanding of vaccines and how they work, the purpose of the study, trial procedures, and perceived trial risks and benefits, an appreciation of their own situation, the discussion and weighing of risks and benefits, discussing the need to consult with others about participation, motivations for participation, and their choice to participate. ConclusionThe results of this study suggest that most adolescents at high risk for HIV demonstrate the key abilities needed to make meaningful decisions about HIV vaccine clinical trial participation.

Willingness to participate in HIV vaccine efficacy trials among high risk men and women from fishing communities along Lake Victoria in Uganda

IntroductionHIV vaccine efficacy trials conducted in suitable populations are anticipated in sub-Saharan Africa. We assessed the willingness to participate in future vaccine trials among individuals from fishing communities along Lake Victoria, Uganda. MethodsFrom July to October 2012, we described a hypothetical vaccine trial to 328 (62.2% men) adults (18–49 years), at risk of HIV infection within 6 months of enrolment in a cohort and assessed their willingness to participate in the trial. Chi-square and logistic regression models were fitted to assess associations between vaccine trial attributes, participants’ characteristics and willingness to participate. ResultsOverall, 99.4% expressed willingness to participate in the hypothetical HIV vaccine trial. This decreased marginally with introduction of particular vaccine trial attributes. Delaying pregnancy for 10 months and large blood draw had the largest effects on reducing willingness to participate to 93.5% (p=0.02) and 94.5% (p=0.01) respectively. All the vaccine trial attributes in combination reduced willingness to participate to 90.6%. This overall reduction in willingness to participate was significantly associated with gender and exchange of gifts for sex in multivariable analysis; women were more than three times as likely to have expressed unwillingness to participate in future vaccine trials as men (aOR=3.4, 95% CI: 1.55, 7.33) and participants who never received gifts in exchange for sex were more than four times as likely to have expressed unwillingness as those who received gifts for sex (aOR=4.5; 95%CI 1.30, 16.70). The main motivators of participation were access to HIV counselling and testing services (31.9%), HIV education (18.0%), hope of being prevented from acquiring HIV (16.6%) and health care (12.5%). ConclusionOur study identifies an important population for inclusion in future HIV prevention trials and provides important insights into acceptability of trial procedures, differences in decisions of women and men and areas for further participant education.

Does message framing predict willingness to participate in a hypothetical HIV vaccine trial: An application of Prospect Theory

It is vital that enough participants are willing to participate in clinical trials to test HIV vaccines adequately. It is, therefore, necessary to explore what affects peoples’ willingness to participate (WTP) in such trials. Studies have only examined individual factors associated with WTP and not the effect of messages about trial participation on potential participants (e.g., whether losses or gains are emphasized, or whether the outcome is certain or uncertain). This study explores whether the effects of message framing on WTP in a hypothetical HIV vaccine trial are consistent with Prospect Theory. This theory suggests that people are fundamentally risk averse and that (1) under conditions of low risk and high certainty, gain-framed messages will be influential (2) under conditions of high risk and low certainty, loss-framed messages will be influential. This cross-sectional study recruited 283 HIV-negative students from a South African university who were given a questionnaire that contained matched certain gain-framed, certain loss-framed, uncertain gain-framed, and uncertain loss-framed statements based on common barriers and facilitators of WTP. Participants were asked to rate how likely each statement was to result in their participation in a hypothetical preventative HIV vaccine trial. Consistent with Prospect Theory predictions, for certain outcomes, gain-framed messages were more likely to result in WTP than loss-framed messages. Inconsistent with predictions, loss-framed message were not more likely to be related to WTP for uncertain outcomes than gain-framed messages. Older students were less likely to express their WTP across the different message frames. Recruitment for HIV vaccine trials should pay attention to how messages about the trial are presented to potential participants.

Motivators of enrolment in HIV vaccine trials: a review of HIV vaccine preparedness studies

HIV vaccine preparedness studies (VPS) are important precursors to HIV vaccine trials. As well, they contribute to an understanding of motivators and barriers for participation in hypothetical HIV vaccine trials. Motivators can take the form of altruism and a desire for social benefits. Perceived personal benefits, including psychological, personal, and financial well-being, may also motivate participation. The authors performed a systematic review of HIV VPS using the Cochrane Database for Systematic Reviews, Medline, PubMed, Embase, and Google Scholar. The authors independently searched the literature for individual HIV VPS that examined motivators of participation in a hypothetical HIV vaccine trial, using the same search strategy. As the denominators employed in the literature varied across studies, the denominators were standardized to the number of respondents per survey item, regardless of their willingness to participate (WTP) in an HIV vaccine trial. The authors retrieved eight studies on social benefits (i.e., altruism) and 11 studies on personal benefits conducted in the Organization for Economic Co-operation and Development (OECD) countries, as well as 19 studies on social benefits and 20 studies on personal benefits in the non-OECD countries. Various different forms of altruism were found to be the major motivators for participation in an HIV vaccine trial in both the OECD and the non-OECD countries. In a large number of studies, protection from HIV was cited as a personal motivator for participation in a hypothetical HIV vaccine trial in the OECD and the non-OECD countries. Knowledge of motivators can inform and target recruitment for HIV vaccine trials, although it must be remembered that hypothetical motivators may not always translate into motivators in an actual vaccine trial.

Willingness of Chinese injection drug users to participate in HIV vaccine trials

Chinese injection drug users (IDUs) may be a proper candidate population for HIV vaccine trials. To evaluate willingness to participate (WTP) in HIV vaccine trials among Chinese IDUs. Questionnaire interviews were completed among 401 IDUs in Urumqi City in northwestern China in 2005. Overall 74.3% of participants said that they would be definitely willing to participate in HIV vaccine trials, 17.7% were probably willing, 6.2% were probably not willing, and remaining 1.8% were definitely not willing to join. Multivariate logistic regression analysis demonstrated that WTP was positively associated with having ever had sex with a drug use partner (adjusted odds ratio [AOR]: 1.8; 95% confidence interval [CI]: 1.04, 3.2), sharing needle and syringe with a new drug use partner in the past 3 months (AOR: 3.8; 95% CI: 1.2, 11.7), perceived family support for participation (AOR: 7.4; 95% CI: 4.3, 12.7), and perceived vaccine protection against HIV infection (AOR: 16.1; 95% CI: 3.7, 70.8), and was negatively associated with perceived risk of social stigma and isolation for participation (AOR: 0.3; 95% CI: 0.2, 0.5). The stated WTP in hypothetical HIV vaccine trials was high among Chinese IDUs. Further studies are needed to evaluate actual enrollment into the trials.

Willingness to participate in HIV vaccine trials: The impact of trial attributes

Objectives. To assess willingness to participate (WTP) in hypothetical Phase III preventive HIV vaccine trials, and the impact of trial attributes on WTP, among low socioeconomic, ethnically diverse adults from communities at elevated risk for HIV infection. Method. Participants ( n = 123; median age = 38; 69% male; 37% Latino; 14% African-American) were recruited in Los Angeles in 2003 using multi-site, venue-based sampling. WTP was assessed for eight hypothetical HIV vaccine trials that varied across seven dichotomous attributes, using a 2 7-4 fractional factorial experimental design. Individual-specific impact of vaccine trial attributes on WTP was estimated using within-individual ANOVA and then meta-analyzed across individuals. Results. Mean WTP for eight hypothetical vaccine trials ranged from 1.74 to 3.81 (1 = highly unlikely, 5 = highly likely). Lower WTP was associated with vaccine-induced infection risk (impact = 0.88, p < 0.0001), false HIV-positives (0.53, p < 0.0001), no provision of free HIV medications (0.52, p < 0.0001), and longer trial duration (0.27; p = 0.0002). Conclusion. HIV vaccine trial attributes may strongly influence WTP. Although existing candidate vaccines cannot cause HIV infection, perceptions of risk may impede WTP. Eliciting trial preferences and concerns prior to trial implementation may enable accommodation of participant preferences and support tailored interventions to address concerns and misconceptions to facilitate enrollment in safe and ethical trials among vulnerable communities.

Knowledge About Vaccine Trials and Willingness to Participate in an HIV/AIDS Vaccine Study in the Ugandan Military

Summary: In preparation for HIV vaccine trials, knowledge about vaccines, willingness to participate in a vaccine study, and motivations for participation must be assessed. The Preparation for AIDS Vaccine Evaluation study assessed knowledge about vaccines and vaccine trials and willingness to participate in a hypothetical trial in 1,182 Ugandan military men (aged 18-30 years). Participants received education about vaccine trials and were interviewed during 24 months of follow-up observation. Its key findings are that: 1) throughout follow-up, most participants expressed willingness to participate in a hypothetical HIV vaccine trial; 2) participants are familiar with vaccines but do not clearly distinguish the use of vaccines for prevention or curing; 3) the most common reason given for being interested in participating in a vaccine trial was to be protected from HIV/AIDS; 4) trials' procedures (e.g., placebos, randomization, and blinding) were unfamiliar; and 5) knowledge about trials' procedures increased incrementally over follow-up, but at different rates for different concepts. These data demonstrate that potential vaccine trials' participants may benefit from vaccine trial education if adequate time is allowed to ensure that participants are able to master the complex information required for trial participation.

Estimation of the direct and indirect effects of vaccination

Indirect effects play a major role in the protection afforded by a vaccination programme. In this work we define new measures of direct, indirect and total (direct + indirect) effects of a vaccination programme in terms of the protection they provide to unvaccinated and vaccinated individuals, and to the entire population. We show how these measures can be estimated using data from a vaccine trial or an observational study. The bias and standard errors of these estimates can be evaluated via stochastic simulations. Examples from a mumps outbreak and a (hypothetical) HIV vaccine trial are used to illustrate the estimation of these new measures of vaccination effectiveness.