Modeling HIV Vaccines in Brazil: Assessing the Impact of a Future HIV Vaccine on Reducing New Infections, Mortality and Number of People Receiving ARV

Abstract

BackgroundThe AIDS epidemic in Brazil remains concentrated in populations with high vulnerability to HIV infection, and the development of an HIV vaccine could make an important contribution to prevention. This study modeled the HIV epidemic and estimated the potential impact of an HIV vaccine on the number of new infections, deaths due to AIDS and the number of people receiving ARV treatment, under various scenarios.Methods and FindingsThe historical HIV prevalence was modeled using Spectrum and projections were made from 2010 to 2050 to study the impact of an HIV vaccine with 40% to 70% efficacy, and 80% coverage of adult population, specific groups such as MSM, IDU, commercial sex workers and their partners, and 15 year olds. The possibility of disinhibition after vaccination, neglecting medium- and high-risk groups, and a disease-modifying vaccine were also considered. The number of new infections and deaths were reduced by 73% and 30%, respectively, by 2050, when 80% of adult population aged 15–49 was vaccinated with a 40% efficacy vaccine. Vaccinating medium- and high-risk groups reduced new infections by 52% and deaths by 21%. A vaccine with 70% efficacy produced a great decline in new infections and deaths. Neglecting medium- and high-risk population groups as well as disinhibition of vaccinated population reduced the impact or even increased the number of new infections. Disease-modifying vaccine also contributed to reducing AIDS deaths, the need for ART and new HIV infections.ConclusionsEven in a country with a concentrated epidemic and high levels of ARV coverage, such as Brazil, moderate efficacy vaccines as part of a comprehensive package of treatment and prevention could have a major impact on preventing new HIV infections and AIDS deaths, as well as reducing the number of people on ARV. Targeted vaccination strategies may be highly effective and cost-beneficial.

Drug Users’ Willingness to Encourage Social, Sexual, and Drug Network Members to Receive an HIV Vaccine: A Social Network Analysis

“…Of note, this study queried participants about their attitudes on and willingness to encourage a 90 % effective vaccine; some previous research indicates that a vaccine of lower efficacy (actual or perceived) may prompt less risk compensation [35–38]. The degree of risk compensation necessary for off-setting the positive effect of a partial, highly efficacious vaccine is likely great [3, 39, 40], particularly when vaccine coverage is high [1, 41]. Thus, although the prospect of developing a vaccine with full efficacy currently appears bleak, continued effort in vaccine development is certainly warranted.…”

“…A preventive HIV vaccine could make a substantial impact on the epidemic [1–3]. However, given that the first vaccines are likely to be only partially effective, successful dissemination among men who have sex with men, people who inject drugs (PWID), and high-risk heterosexual populations will be critical [1].…”

“…However, given that the first vaccines are likely to be only partially effective, successful dissemination among men who have sex with men, people who inject drugs (PWID), and high-risk heterosexual populations will be critical [1]. Unfortunately, research on potential strategies for achieving adequate coverage among high-risk populations is currently lacking.…”

Relationship-level analysis of drug users' anticipated changes in risk behavior following HIV vaccination

“…However, early vaccines on the market are likely to be only partially effective, and post-vaccination increases in risk behavior (i.e., risk compensation (Hogben & Liddon, 2008)) could reduce the public health benefit (Andersson et al, 2007; Blower, Schwartz, & Mills, 2003; Eaton & Kalichman, 2007; Fonseca et al, 2010; Gray et al, 2003). Findings from previous studies examining individuals’ likelihood of risk compensation have been mixed; when queried about others’ behaviors, study participants reported a likely increase in sexual risk behavior if vaccinated (Koniak-Griffin, Nyamathi, Tallen, González-Figueroa, & Dominick, 2007; Newman et al, 2009; Newman, Roungprakhon, Tepjan, Yim, & Walisser, 2012; Olin et al, 2006; Sayles, MacPhail, Newman, & Cunningham, 2010; Webb, Zimet, Mays, & Fortenberry, 1999).…”

What impact would an HIV/AIDS vaccine have on the HIV/AIDS epidemic in Kenya?

“…The International AIDS Vaccine Initiative (IAVI) and the Futures Institute have worked together to develop a mathematical model to study the potential impacts of an HIV vaccine on the pandemic both globally [4], and in countries such as Kenya, China, Uganda and Brazil [5]. In Kenya, IAVI developed this research in collaboration with the Kenya HIV and AIDS Research Coordinating Mechanism (KARSCOM) and a team of researchers at the Kenya AIDS Vaccine Initiative (KAVI) led the technical work with assistance from the Futures Institute.…”