Candidate hepatitis C vaccine trials and people who inject drugs: Challenges and opportunities

National Centre in HIV Epidemiology and Clinical Research, School of Public Health and Community Medicine, University of New South Wales, Centre for Immunology, Darlinghurst, NSW 2010, Australia.
Vaccine (Impact Factor: 3.62). 10/2010; 28(45):7273-8. DOI: 10.1016/j.vaccine.2010.08.085
Source: PubMed


People who inject drugs (PWID) are at high risk of HCV. Limited evidence of the effectiveness of prevention interventions and low uptake of treatment in this group highlight the need for increased investment in biomedical interventions, notably safe and efficacious vaccines. While several candidates are currently in development, field trials in PWID present challenges, including ethical issues associated with trial literacy, informed consent and standards of care. Significant biological and social factors and differences between HIV and HCV suggest that HCV warrants targeted vaccine preparedness research to lay the groundwork for successful implementation of future trials.

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Available from: Lisa Maher
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    • "As the key population at risk of HCV in developed countries [13], effective engagement and recruitment of large numbers of exposed but uninfected PWID will be required for successful Phase III vaccine trials. Trials of candidate HCV vaccines are likely to face particular challenges in attracting and retaining suitable participants and in developing appropriate protocols to assess safety, immunogenicity and efficacy [1]. The identification of populations with sufficiently high HCV incidence to demonstrate vaccine candidate efficacy will be of particular importance. "
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    ABSTRACT: Efficacy trials of preventive hepatitis C virus (HCV) vaccine candidates raise challenging scientific and ethical issues. Based on data from the first 3years of a community-based prospective observational study - the Hepatitis C Incidence and Transmission Study-community (HITS-c) - this paper examines the feasibility of conducting trials of candidate HCV vaccines with people who inject drugs (PWID) in Sydney, Australia. Of the 166 PWID confirmed HCV antibody negative and eligible for enrolment, 156 (94%) completed baseline procedures. Retention was high, with 89% of participants retained at 48weeks and 76% of participants completing at least 75% of study visits within 2weeks of schedule. The rate of primary HCV infection was 7.9/100py (95% CI 4.9, 12.7). Of the 17 incident cases, 16 completed at least one follow-up assessment and 12 (75%) had evidence of chronic viraemia with progression to chronic HCV infection estimated to be 6/100py. Power calculations suggest a chronic HCV infection rate of at least 12/100py (primary HCV infection rate 16/100py) will be required for stand-alone trials of highly efficacious candidates designed to prevent chronic infection. However, elevated primary HCV infection was observed among participants not receiving opioid substitution therapy who reported heroin as the main drug injected (26.9/100py, 95% CI 14.5, 50.0) and those who reported unstable housing (23.5/100py, 95% CI 7.6, 72.8), daily or more frequent injecting (22.7/100py, 95% CI 12.2, 42.2) and receptive syringe sharing (23.6/100py, 95% CI 9.8, 56.7) in the 6months prior to baseline. These data suggest that it is possible to recruit and retain at-risk PWID who adhere to study protocols and that modification of eligibility criteria may identify populations with sufficiently high HCV incidence. Results support the feasibility of large multi-centre HCV vaccine trials, including in the Australian setting.
    Full-text · Article · Aug 2014 · Vaccine
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    • "Trial duration, in addition to flexibility in appointment times and days and travel time may be important factors to be negotiated during trial design in order to optimise enrolment and retention. Questions asked by our contingent group about guarantees of health compensation in the event of vaccine-related side effects have also been identified in HIV VPS (Strauss et al., 2001) highlighting the importance of ethical concerns surrounding HCV vaccine trials, particularly standard of care and informed consent (Maher et al., 2010b). Addressing such issues may improve trial enrolment rates and also work to alleviate the prevailing mistrust of health authorities and governments among PWID (Brooks et al., 2007; Harrison, 2001). "
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    ABSTRACT: A safe and efficacious vaccine may be the most efficient and cost-effective strategy for controlling the hepatitis C virus (HCV) epidemic among people who inject drugs (PWID) and several candidates are in development. However, little is known about the factors that influence willingness to participate (WTP) in candidate HCV vaccine trials among this group. HCV seronegative PWID recruited between 2008 and 2010 as part of a prospective observational cohort study in Sydney, Australia were asked whether they would be willing to participate in a future candidate hepatitis C vaccine trial and to provide reasons to explain their decision. Of 113 participants, 74% indicated WTP, 15% were unwilling to participate and 11% reported WTP that was contingent on vaccine characteristics and trial design issues. The most commonly reported motivator for hypothetical trial participation was altruism, followed by potential health benefits, financial remuneration, and knowledge gain. Barriers to hypothetical participation included fears about possible harms to health, such as concerns about vaccine safety, side effects, and acquiring HCV from the vaccine; other barriers included mistrust of biomedical research and time constraints. These results may be useful in designing strategies to enhance HCV vaccine trial recruitment and retention and have ethical implications for developing informed consent processes and standards of care.
    Full-text · Article · Nov 2011 · Drug and alcohol dependence
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    • "The HITS-c study was designed to inform future trials of candidate HCV vaccines in Sydney, Australia. Following 10 months of formative ethnographic fieldwork , field sites were established in several Sydney neighborhoods (Maher et al., 2010) using a purpose built study van. Participants were recruited using a combination of respondent-driven sampling (Heckathorn, 1997) and direct approaches. "
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    ABSTRACT: Hepatitis C virus (HCV) infection is a significant global public health problem. In developed countries, 90% of new infections occur among people who inject drugs (PWID), with seroprevalence increasing rapidly among new injectors. Staying Safe is an international, qualitative, social research project, the aim of which is to draw on the experiences of long-term PWID to inform a new generation of HCV prevention strategies. The Sydney project team employed life history interviews and computer-generated timelines to elicit detailed data about unexposed participants' (n =13) injecting practices, circumstances, and social networks over time. The motivations and strategies that enabled participants to avoid risk situations, and which might have helped them to "stay safe," appeared not to be directly related to harm-reduction messages or HCV avoidance. These included the ability and inclination to maintain social and structural resources, to mainly inject alone, to manage withdrawal, and to avoid injecting-related scars. These findings point to the multiple priorities that facilitate viral avoidance among PWID and the potential efficacy of nonspecific HCV harm-reduction interventions for HCV prevention.
    Full-text · Article · Aug 2011 · Qualitative Health Research
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