With the continued rollout and implementation of global, national, and regional HIV incidence targets and timelines, one thing has become abundantly clear: reducing HIV rates below endemic and epidemic levels in all vulnerable populations and subpopulations everywhere in the world will require not only a monumental scale-up of care and antiretroviral therapy for those living with the virus, but also fierce commitment to primary biomedical prevention. This isn't simply rhetoric, but rather a public health mandate that is supported by a growing body of epidemiological and other scientific data.
However, only a fraction of adolescents and adults vulnerable to HIV are accessing one on the most important evidence-based additions to the prevention toolbox: coformulated tenofovir disoproxil fumarate and emtricitabine (Truvada; TDF/FTC) as a pre-exposure prophylaxis (PrEP). In the U.S. alone, where TDF/FTC has been approved as PrEP since July 2012, of the 1.2 million adults with indications for PrEP—a likely conservative estimate from the U.S. Centers for Disease Control and Prevention (CDC)—only an estimated 4% have used it, even briefly. For PrEP to have a population-level effect in the U.S., however, a substantial increase in PrEP uptake will be required: 40% use among high-risk men who have sex with men, 10% use among people who inject drugs, and 10% use among high-risk heterosexuals would be in the absence of any improvements in clinical care engagement and viral load suppression rates among people living with HIV, necessary to prevent approximately 48,000 new infections between 2015 and 2020.
Significant barriers to PrEP uptake exist, with the most egregious examples being achingly slow product registration and national health plan inclusion—the high cost of TDF/FTC, along with limited cost-effectiveness data, are considerable factors8—in many high-, middle-, and low-income countries. Even where PrEP has been approved, myriad access challenges exist. Examples in the U.S. include restrictions in CDC and other federal agency funds to pay for TDF/FTC; reluctance to expand Medicaid in many states, particularly those with high HIV prevalence and incidence estimates; and lags in awareness of PrEP and best screening, prescribing, and monitoring practices among primary care providers. Implementation strategies to overcome these structural hindrances, on top of myriad social and behavioral barriers, will be critical for PrEP's success.