Abstract
BackgroundExpanded HIV prevention options are needed to increase uptake of HIV prevention among women, especially in generalized epidemics. As the dapivirine vaginal ring moves forward through regulatory review and open-label extension studies, the potential public health impact and cost-effectiveness of this new prevention method are not fully known. We used mathematical modeling to explore the impact and cost-effectiveness of the ring in different implementation scenarios alongside scale-up of other HIV prevention interventions. Given the knowledge gaps about key factors influencing the ring’s implementation, including potential uptake and delivery costs, we engaged in a stakeholder consultation process to elicit plausible parameter ranges and explored scenarios to identify the possible range of impact, cost, and cost-effectiveness.Methods and findingsWe used the Goals model to simulate scenarios of oral and ring pre-exposure prophylaxis (PrEP) implementation among female sex workers and among other women ≤21 years or >21 years with multiple male partners, in Kenya, South Africa, Uganda, and Zimbabwe. In these scenarios, we varied antiretroviral therapy (ART) coverage, dapivirine ring coverage and ring effectiveness (encompassing efficacy and adherence) by risk group. Following discussions with stakeholders, the maximum level of PrEP coverage (oral and/or ring) considered in each country was equal to modern contraception use minus condom use in the two age groups.We assessed results for 18 years, from 2018 to 2035. In South Africa, for example, the HIV infections averted by PrEP (ring plus oral PrEP) ranged from 310,000 under the highest-impact scenario (including ART held constant at 2017 levels, high ring coverage, and 85% ring effectiveness) to 55,000 under the lowest-impact scenario (including ART reaching the UNAIDS 90-90-90 targets by 2020, low ring coverage, and 30% ring effectiveness). This represented a range of 6.4% to 2.2% of new HIV infections averted. Given our assumptions, the addition of the ring results in 11% to 132% more impact than oral PrEP alone. The cost per HIV infection averted for the ring ranged from US$13,000 to US$121,000.ConclusionsThis analysis offers a wide range of scenarios given the considerable uncertainty over ring uptake, consistency of use, and effectiveness, as well as HIV testing, prevention, and treatment use over the next two decades. This could help inform donors and implementers as they decide where to allocate resources in order to maximize the impact of the dapivirine ring in light of funding and implementation constraints. Better understanding of the cost and potential uptake of the intervention would improve our ability to estimate its cost-effectiveness and assess where it can have the most impact.
Highlights
Despite successes in scaling up antiretroviral therapy (ART) in many countries, which can help reduce HIV transmission when viral load suppression is achieved, there are still as many as 1.8 million new HIV infections annually
In South Africa, for example, the HIV infections averted by pre-exposure prophylaxis (PrEP) ranged from 310,000 under the highest-impact scenario to 55,000 under the lowest-impact scenario
National AIDS Impact Module (AIM) files are publicly available in Spectrum and are updated and validated annually by Ministry of Health staff in each country in a process coordinated by the Joint United Nations Programme on HIV/AIDS (UNAIDS) to produce national, regional, and global estimates of HIV burden
Summary
Despite successes in scaling up antiretroviral therapy (ART) in many countries, which can help reduce HIV transmission when viral load suppression is achieved, there are still as many as 1.8 million new HIV infections annually. Post-hoc exploratory analyses suggested that HIV risk was reduced by up to 75% among a subset of participants who appeared to have better adherence [5] As these results are influenced by challenges in quantifying adherence due to measurement error of drug levels in the ring, the effectiveness of the ring at near-perfect adherence may be even higher. Further data are anticipated from two recently completed open-label extension (OLE) studies, HOPE and DREAM, in which ring was provided to previous Phase III trial participants Preliminary findings from these two studies suggest higher overall levels of adherence, leading to higher effectiveness (estimated to be around 50% using modeling), than were seen during the Phase III trials, similar to the experience with oral PrEP in Phase III versus OLE [6,7,8]. Given the knowledge gaps about key factors influencing the ring’s implementation, including potential uptake and delivery costs, we engaged in a stakeholder consultation process to elicit plausible parameter ranges and explored scenarios to identify the possible range of impact, cost, and cost-effectiveness.
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