A Network Approach to Determine Optimization of PrEP Uptake in Athens, Greece.

Although the HIV epidemic in Athens, Greece has reemerged and spread in men who have sex with men (MSM), state-supported PrEP programs have not been instituted. A PrEP intervention was implemented building upon an existing network cohort of MSM (308 participants; 1212 network members). A PrEP intervention cohort of 106 participants was selected based upon sex behaviors. Individual, partner, and network characteristics were compared between the cohorts. The PrEP cohort members were more highly connected and in more influential positions in the network than their peers. Further, their sexual network connections' behaviors increased their vulnerability to HIV infection relative to the rest of the network's sex partners. This included greater stimulant use (24.2% vs 7.0%; χ = 28.2; p < 0.001), greater rates of at least weekly condomless sex (OR = 2.7; 95% CI 2.1-3.5; χ = 59.2; p < 0.001) and at least weekly use of drugs or alcohol during sex (OR = 3.4; 95% CI 2.6-4.3; χ = 89.7; p < 0.001). Finally the PrEP cohort's social networks showed similarly increased vulnerability to seroconversion, including greater rates of injection drug use (4.1% vs 0.5%; χ = 3.9; p = 0.04), greater stimulant use (33.6% vs 14.6%; χ = 16.9, p < 0.001), and higher rates of recent STIs (21.6% vs 13.1%; χ = 4.4; p = 0.04). Thus, this PrEP intervention engaged individuals in vulnerable positions with vulnerable connections within an MSM community.