Abstract
BACKGROUND AND AIMS: The advent of highly effective hepatitis C (HCV) treatments has questioned the need for a vaccine to control HCV amongst people who inject drugs (PWID). However, high treatment costs and ongoing reinfection risk suggest it could still play a role. We compared the impact of HCV vaccination amongst PWID against providing HCV treatment. METHODS: Dynamic HCV vaccination and treatment models among PWID were used to determine the vaccination and treatment rates required to reduce chronic HCV prevalence or incidence in the UK over 20 or 40 years. Projections considered a low (50% protection for 5 years), moderate (70% protection for 10 years) or high (90% protection for 20 years) efficacy vaccine. Sensitivities to various parameters were examined. RESULTS: To halve chronic HCV prevalence over 40 years, the low, moderate and high efficacy vaccines required annual vaccination rates (coverage after 20 years) of 162 (72%), 77 (56%) and 44 (38%) per 1000 PWID, respectively. These vaccination rates were 16, 7.6 and 4.4 times greater than corresponding treatment rates. To halve prevalence over 20 years nearly doubled these vaccination rates (moderate and high efficacy vaccines only) and the vaccination-to-treatment ratio increased by 20%. For all scenarios considered, required annual vaccination rates and vaccination-to-treatment ratios were at least a third lower to reduce incidence than prevalence. Baseline HCV prevalence had little effect on the vaccine’s impact on prevalence or incidence, but substantially affected the vaccination-to-treatment ratios. Behavioural risk heterogeneity only had an effect if we assumed no transitions between high and low risk states and vaccinations were targeted or if PWID were high risk for their first year. CONCLUSIONS: Achievable coverage levels of a low efficacy prophylactic HCV vaccine could greatly reduce HCV transmission amongst PWID. Current high treatment costs ensure vaccination could still be an important intervention option.
JS acknowledges funding from a PhD
scholarship from the Engineering and Physical
Sciences Research Council (EPSRC); MHi, PV and
NKM acknowledge support from the National Institute
for Health Research (NIHR) Health Protection
Research Unit on Evaluation of Interventions; NKM
acknowledges research funding from the National
Institute for Drug Abuse (R01 DA037773-01A1) and
the University of California San Diego Center for
AIDS Research(CFAR), an NIH-funded program (P30
AI036214), which is supported by the following NIH
Institutes and Centers: NIAID, NCI, NIMH, NIDA,
NICHD, NHLBI, NIA, NIGMS, and NIDDK. NS is the
recipient of a Burnet Institute Jim and Margaret
Beever fellowship; EM, HD and MHe are the
recipients of National Health and Medical Research
Council fellowships.
Project
- HCV Elimination Modelling
Providing evidence-based policy recommendations for prevention, testing and treatment of Hepatitis C.