Strategies to reduce new HIV infections span multifaceted efforts, including safe-sex counseling, voluntary medical male circumcision, treatment as prevention, and pre- (PrEP) and postexposure prophylaxis. PrEP entails the use of antiretroviral (ARV) drugs prophylactically by HIV-negative individuals at risk of infection to thwart acquisition of the virus.
In 2012, the US Food and Drug Administration (FDA) approved Truvada, a daily oral pill for PrEP comprising 2 reverse tranÂscriptase inhibitors, tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC). This landmark approval was followed by approval from several other countries in North America and South America, Europe, and Africa. Support for oral PrEP emerged through pivotal randomized controlled trials invesÂtigating Truvada in men who have sex with men (MSM),1-3 serodiscordant heterosexual couples in Kenya and Uganda,4 heterosexual men and women in Botswana,5 and users of injecÂtion drugs in Thailand.6 The 2015 guidelines from the World Health Organization recommend oral PrEP for all populations at significant risk of HIV infection.7
ONE APPROACH DOESN’T FIT ALL
Clinical findings for oral PrEP in healthy participants demonstrated efficacy but also illuminated the imporÂtance of user adherence for protection. For example, the first randomized controlled trial for PrEP (iPrEx, daily oral TDF and FTC in MSM) showed a 44% reduction in HIV acquisition but protection as high as 92% in the subset of individuals with detectable levels of tenofovir in the plasma.8 Importantly, oral PrEP is particularly unforgiving for women, with over 5 doses per week required to confer protection from vaginal exposure. As the FEM-PrEP9 and the VOICE10 clinical trials underscored, inconsistent use (or low adherence)11,12 of daily oral and vaginal ARV-based prevenÂtion products among the participating women resulted in no protection against HIV. Research about product preference in hypothetical settings or with actual products has shown that no single product is appealing across different groups of women and that a diversification of drug delivery forms is needed to optimize prevention coverage.13-15 Because PrEP is an elective tactic for HIV prevention, the ability of an individual to select a product that suits his or her lifestyle from an array of options may enhance the likeÂlihood of adherence.