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UBC Theses and Dissertations

Cognitive factors and willingness to participate in an HIV vaccine trial in injection drug users Dhalla, Shayesta


HIV vaccine preparedness studies (VPS) are important precursors of vaccine trials, assessing the feasibility of such trials. This thesis presents a study of HIV vaccine preparedness, with a focus on the investigation of cognitive factors as predictors of willingness to participate (WTP) in preventive and therapeutic HIV vaccine trials. These cognitive factors include HIV treatment optimism, self-efficacy beliefs, and knowledge of HIV vaccine trial concepts. The introductory chapter covers HIV epidemiology, prevention measures including HIV vaccines, background information on HIV VPS and HIV vaccines, and a description of cognitive factors potentially associated with WTP. Chapters 2 and 3 are review articles: one describing retention rates (17 studies) and WTP (22 studies) in the Organization for Economic Co-operation and Development (OECD) countries, and the other in the non-OECD countries (16 studies on retention; 21 studies on WTP). The studies indicated that high-risk factors were positively associated with WTP and that retention and WTP were adequate for conducting HIV vaccine trials. Chapter 4 consists of a VPS involving HIV-negative injectors in the Vancouver Injection Drug Users’ (VIDUS) study. This study found that Aboriginal ethnicity, educational level (≥ high school), and an increase in self-efficacy had statistically significant positive associations with WTP. The majority of participants in this study had relatively high levels of self-efficacy so we are most confident about this relationship at such levels. HIV treatment optimism and knowledge of HIV vaccine trial concepts were unrelated to WTP. Chapter 5, using the AIDS Care Cohort to Evaluate Exposure to Survival Services (ACCESS) study in HIV-positive injectors, demonstrated that self-efficacy again had a statistically significant positive association with WTP. Again, the majority of participants had high levels of self-efficacy. HIV treatment optimism and knowledge were unrelated to WTP. These studies address a gap in knowledge of cognitive factors regarding relation to WTP in HIV vaccine trials. In conclusion, Chapter 6 discusses 1) a summary of the findings and comparisons between the studies 2) novelty (3) strengths and weaknesses (4) implications and (5) future directions.

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