Allocating Antiretrovirals in South Africa: Using Modeling to Determine Treatment Equity

University of California, Los Angeles, Los Ángeles, California, United States
PLoS Medicine (Impact Factor: 14.43). 07/2005; 2(6):e155; author reply e186. DOI: 10.1371/journal.pmed.0020155
Source: PubMed
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    ABSTRACT: Current HIV vaccines in development appear unlikely to prevent infection, but could provide benefits by increasing survival; such vaccines are described as disease-modifying vaccines. We review the current status of vaccines and modeling vaccines. We also predict the impact that disease-modifying vaccines could have in South Africa, where multiple subtypes are co-circulating. We model transmissibility/fitness differences among subtypes. We used uncertainty analyses to model vaccines with four characteristics: (i) take, (ii) duration of immunity, (iii) reduction in transmissibility/fitness, and (iv) increase in survival. We reconstructed, and forecasted, the South African epidemic from 1940 to 2140 (assuming no vaccination). We predict that: (i) incidence will peak in 2014, decline, and stabilize, (ii) prevalence will continue to rise, and (iii) the AIDS death rate curve will peak in 2022. Our predictions show that (over the next 135 years) the epidemic in South Africa will switch from a predominantly Subtype C epidemic to an epidemic driven by other subtypes. We predict that the epidemic could remain unchanged, even with mass vaccination with a vaccine that is equally effective against all co-circulating subtypes. However, if the non-C subtypes are less (or equally) transmissible as Subtype C then disease-modifying vaccines could result in eradication. Thus, in countries where multiple-subtypes are co-circulating it is critical to realize that small biological differences among subtypes will have dramatic consequences for the effectiveness of HIV vaccination campaigns. A slight difference in fitness will determine whether a disease-modifying vaccine has almost no impact on the epidemic or can achieve eradication.
    Current Drug Targets - Infectious Disorders 07/2005; 5(2):179-92. DOI:10.2174/1568005054201616
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    ABSTRACT: Highly active antiretroviral therapy has markedly reduced HIV morbidity and mortality in industrialized countries. Expanded access to the 6.5 million individuals in immediate need of antiretroviral therapy using a public-health-systems approach is now promulgated as an international policy. An approximate 1.6 million individuals have already accessed antiretroviral therapy within programs in resource-poor settings. Early studies from these treatment programs confirm similar virologic and immunologic responses to antiretroviral therapy as were observed earlier in industrialized settings. While medium-term reductions in morbidity and mortality also parallel those reported from Europe and North America, of particular concern is the observation that mortality immediately after starting antiretroviral therapy in resource-poor settings is several-fold higher than that of similar patients initiating antiretroviral therapy in industrialized settings. This early mortality is multifactorial and is both a reflection of a very high preantiretroviral therapy mortality and a variety of factors such as comorbid conditions, late presentation, immune restoration disease, together with limited treatment and diagnostic options. Causes of mortality immediately prior to and during early antiretroviral therapy are reviewed and strategies to reduce mortality are identified and discussed.
    Current opinion in HIV and AIDS 08/2007; 2(4):346-51. DOI:10.1097/COH.0b013e3281e72cbd · 4.68 Impact Factor

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