Individuals who inject drugs should use pre-exposure prophylaxis (PrEP)

Injection drug use (IDU) was responsible for 6% of incident HIV infections in 2017, while IDU and male-to-male sexual contact were responsible for another 3%. (CDC, 2018). Individuals who use drugs are at higher risk of HIV transmission and acquisition due to specific drug use behaviors (e.g., IDU, sharing of needles and other drug paraphernalia; CDC, 2018) as well as participation in high-risk sexual behaviors that may co-occur with drug use (e.g., unprotected sexual encounters; CDC, 2018). (Brown, Eriksen, Gause, Brody, & Sales, 2018). Increased IDU caused by the opiate pandemic has also been related to more HIV infections in rural areas of the United States (for example, 215 HIV cases in midwestern Scott County, Indiana; (Conrad et al., 2015).

Pre-exposure prophylaxis (PrEP) is the use of antiretroviral (ARV) drugs by HIV-uninfected people to prevent HIV infection before they are exposed to HIV (Young & McDaid, 2014). Emtrictabine/tenofovir disoproxyl fumarate (Truvada®) was approved by the US Food and Drug Administration (FDA) in 2012 for the prevention of HIV infection in adults; this combination drug was later approved for use in adolescents weighing 35 kg or more. Emtricitabine/tenofovir alafenamide (Descovy®) was approved by the US Food and Drug Administration in 2019 for the prevention of HIV infection through sexual acquisition in adults and adolescents weighing 35 kg or more, excluding persons who are at risk of HIV through receptive vaginal intercourse. Emtricitabine/tenofovir alafenamide is therefore not yet licensed for HIV prophylaxis in cisgender women or those who are at risk from injecting drugs. Both drugs have been licensed for use in conjunction with behavioral HIV prevention strategies (e.g., safer sexual practices, use of sterile injection equipment). The Centers for Disease Control and Prevention (CDC) updated its clinical practice guidelines for PrEP use in 2017. (CDC, 2018). PrEP is recommended for HIV-uninfected adults who have reported any injection of drugs not prescribed by a clinician in the previous 6 months, as well as any of the following: a) any sharing of injection or drug preparation equipment in the previous 6 months; or b) any risk of sexual HIV acquisition in the previous 6 months (CDC, 2018). According to the CDC recommendations, roughly 18.5 percent of injectable drug users in the United States are at considerable HIV risk and would be eligible for PrEP (Smith et al., 2015).

PrEP has been shown to be effective in preventing HIV infection in high-risk groups such as serodiscordant heterosexual couples (Baeten et al., 2012), heterosexual men and women (Thigpen et al., 2012), men who have sex with men (MSM), and transgender women (Thigpen et al., 2012). (Grant et al., 2010). An HIV infection incidence of 2.03 percent in PrEP conditions and 4.07 percent in control conditions was found in a meta-analysis of seven randomized controlled trials of PrEP efficacy (N=14,804) (Jiang et al., 2014). Furthermore, the results of the primary randomized controlled trial of PrEP among those who inject drugs in Thailand showed a 51.8 percent reduction in HIV incidence among those who took tenofovir compared to those who took placebo (Choopanya et al., 2013). A later analysis revealed that those with 97.5 percent or above adherence had an 83.5 percent lower risk of new HIV infections (Martin et al, 2015). Despite mounting evidence of PrEP's effectiveness in preventing new HIV infections, widespread access and use of PrEP among at-risk populations in the United States, particularly among drug users, has remained limited (Hacker, Cohn, Golden, & Heumann, 2017).

PrEP uptake among people who inject drugs is low, which could be attributed to a lack of knowledge among this group. For example, only 13.4% of those who had injected drugs in the previous year had heard of PrEP, and none of the participants said they knew of someone who had used PrEP in the previous year (Kuo et al., 2016). Similarly, just a quarter of people seeking syringe exchange programs had heard of PrEP, and only two out of 265 people said they were currently using it (Sherman et al., 2019). Despite minimal awareness of PrEP, some studies suggest that those who inject drugs may be willing to use it. For example, 42.7 percent of individuals who had used injectable drugs in the previous year said they were "very likely" to use PrEP, 23.5 percent said they were "somewhat likely," and 29.3 percent said they were "not likely" to use PrEP (Kuo et al., 2016). Similarly, in Vancouver, Canada, one-third of HIV-negative injecting drug users (35.4 percent) said they would use PrEP (Escudero et al., 2015). Individuals seeking syringe exchange programs were more willing to use PrEP, according to Sherman and colleagues (2019), with 63 percent expressing interest.