The cost-effectiveness of a modestly effective HIV vaccine in the United States
Introduction
Despite dramatic increases in the availability of antiretroviral therapy for HIV in resource-limited settings, approximately two new infections occur worldwide for every person placed on treatment [1]. This observation highlights the urgent need for expanded HIV prevention efforts, including use of an HIV vaccine. After many years of disappointing results, several promising developments have provided more cause for optimism [2]. In 2009, a large phase III trial of an ALVAC and AIDSVAX vaccine (RV144) demonstrated modest protection from infection with HIV, with a 31% reduction among trial volunteers [3]. More recently, investigators have reported the development of broadly neutralizing antibodies, which provides potential new targets for vaccine development [4], [5].
The modest success of the RV144 trial prompted renewed interest in understanding whether the use of a partially effective HIV vaccine would improve health outcomes sufficiently to justify its use [6], [7], [8], [9], [10], [11]. In particular, although the RV144 trial showed an overall effectiveness of 31%, vaccine efficacy was likely higher (approximately 70%) in the first year and rapidly declined over time. Given such a modestly effective vaccine, it is unknown to what extent a universal vaccination campaign, or one that prioritizes key populations, will reduce overall HIV incidence in the population.
As part of a collaboration established by the Centers for Disease Control and Prevention (CDC) and the Joint United Nations Programme on HIV/AIDS (UNAIDS), we evaluated the health and economic outcomes resulting from broad use of a partially effective HIV vaccine in the United States. Our analysis assumed declining vaccine efficacy as observed in the RV144 trial. We evaluated three strategies: one-time vaccination; vaccination followed by booster vaccinations at three- or five-year intervals; and a hybrid strategy, in which sub-populations at higher risk of HIV exposure received booster vaccinations. We evaluated the effect of these strategies on HIV incidence, infections averted, life expectancy, quality-adjusted life expectancy, costs, and cost-effectiveness.
Section snippets
Methods
Applying our previously published HIV vaccine model [6], we incorporated the 2009 ALVAC/AIDSVAX randomized clinical trial results to consider the effects of such a modestly effective HIV vaccine on population health outcomes and cost-effectiveness [3]. Additional model details can be found elsewhere [6], [12]. The model was implemented in the mathematical programming language Matlab 2010b.
Results
With no HIV vaccination program, we estimated that approximately 590,000 new HIV infections will occur in the United States over the next 10 years, with 47% of cases occurring among MSM, 20% among PWID, 6% among MSM/PWID, and 27% among heterosexually exposed populations.
Discussion
In this model-based analysis for the United States, we estimated the population health and economic outcomes that would result from use of an HIV vaccine with efficacy similar to that observed in the RV144 trial. Over the three years of the RV144 trial, use of the vaccine reduced new infections by 31%. However, the efficacy of the vaccine was potentially higher during the first year and subsequently declined rapidly, and our analysis was designed to reflect this declining efficacy. Because of
Acknowledgements
This work was supported by a grant from the National Institute on Drug Abuse, United States National Institutes of Health (R-01-DA-15612) and the United States Department of Veterans Affairs.
Conflict of interest: Each author reports no conflict of interest or any external financial support that is relevant to this study. Funding: Our funding sources had no role in the design of the study, in the collection, analysis, and interpretation of data, in the writing of the manuscript, and in the
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