A new modeling study recently published in the Journal of Acquired Immune Deficiency Syndromes estimated that more than 30% of HIV infections in the United States could be prevented if at least 25% of men who have sex with men at risk for HIV receive pre-exposure prophylaxis, or PrEP.
This estimate exceeds a goal set by the United States’ National HIV/AIDS Strategyto reduce 25% of new infections by 2020, according to Michael T. LeVasseur, PhD, MPH, a biostatistician in the department of epidemiology and biostatistics at Dornsife School of Public Health, Drexel University, and colleagues.
“We know that PrEP is highly effective at preventing HIV infection. What we don’t know is how much of an impact it will have at the population level considering the numerous behavioral strategies that men use to prevent infection,” LeVasseur said in a press release. “This study attempts to answer that question, and future work with this model will attempt to identify specific strategies that will work best to stop the transmission of HIV.”
LeVasseur and colleagues’ analysis included data from 10,000 men who have sex with men (MSM) — a population that accounted for 82% of all new HIV infections among adult and adolescent men in the U.S. in 2015. Of these men, 19% were assumed to have HIV, 44% of whom were unaware of their infection, and 36.9% of HIV-negative men had not been tested in the past year.
The model predicted that 103.2 HIV infections per 10,000 MSM would occur in the absence of any HIV prevention strategy. When PrEP alone was assigned to 1% of the cohort, approximately 1.6% of infections were averted. Increasing uptake to 25% of the cohort was estimated to prevent 30.7% of infections.
Without PrEP, condom use alone prevented 48.8% infections; seroadaptive behavioral strategies prevented 37.7% of infections; HIV treatment as prevention averted 27.1% of infections; and all three interventions combined prevented 72.2% of infections. Adding PrEP use in this model simulation to 25% of the cohort prevented an additional 5% of infections.
“PrEP is just another ‘tool in the toolbox’ for HIV prevention, but it is an important one,” LeVasseur said in the release.
Despite its benefit, a separate study published in AIDS Patient Care and STDs found that only 3.4% of young men who have sex with men surveyed in the U.S. had ever used PrEP.
“[Uptake is] probably low because of a lack of knowledge among patients, as well as providers, coupled with high costs,” LeVasseur said.
In June, the FDA approved the first generic version of Truvada(emtricitabine/tenofovir disoproxil fumarate, Gilead Sciences; FTC/TDF) as PrEP for uninfected adults at high risk for HIV. Although costs can still be high, LeVassseur said in the release that PrEP is now covered by most health insurance companies.
In addition to preventing HIV, LeVasseur noted that PrEP may also offer a psychological benefit.
“Many MSM have felt significant anxiety around sexual intimacy due to fear of HIV infection, even with condom use, frequent HIV testing and seroadaptive techniques,” he said in the release. “Highlighting how effective these prevention methods are would certainly lead to an increase in PrEP uptake and easing of the mind.” – by Stephanie Viguers