Abstract
BACKGROUND: Pre-exposure prophylaxis (PrEP) and HIV treatment as prevention, which underlies the Undetectable = Untransmittable (U = U) campaign, are two effective biomedical approaches for HIV prevention among sexual minority men (SMM). Attitudes toward PrEP and U = U may differ between SMM emerging adults (EA: 18-24 years old) and young adults (YA: 25-29 years old) to drive differences in sexual behavior. However, to date, few studies assessed the degree to which YAs and EAs differ in their beliefs in the effectiveness of PrEP and U = U. METHOD: A national sample of 80 SMM in the USA (M(age) = 25.1 years; 53.7% racial/ethnic minority; 38.8% EA; 61.3% YA) participated in a 6-month mHealth intervention for PrEP adherence. Non-parametric tests assessed differences in sexual behaviors and attitudes toward the effectiveness of PrEP and U = U between EAs and YAs using baseline data. RESULTS: Compared to EAs, higher proportions of YAs trusted PrEP's effectiveness and considered condom use unnecessary after taking PrEP. More YAs than EAs were willing to engage in sexual behaviors that they felt too risky before learning about U = U and were more comfortable having condomless sex with HIV-positive partners. Conversely, a greater proportion of EAs than YAs preferred to use condoms even when their partners are on anti-HIV medications. CONCLUSION: Overall, YAs trusted the effectiveness of U = U and PrEP more than EAs, underscoring developmental differences in SMM's perspectives on biomedical HIV prevention tools. Our findings underscore the importance of tailoring messages on biomedical HIV prevention options differently for EAs and YAs to optimize uptake.