Prevalence of HSV-1 and HSV-2 among young gay and bisexual men and their association with HIV and other risk factors: findings from the P18 Cohort Study.

Herpes Simplex Virus types 1 and 2 (HSV-1 and HSV-2) are prevalent STIs among men who have sex with men (MSM), yet remain underexamined in the U.S.. Data from the P18 cohort sub-study, P18 Viral (N = 520), were used to examine factors associated with HSV-1 and HSV-2 infection among a sample of young adult cisgender gay men. We aimed to assess (1) the seroprevalence rates of HSV-1 and HSV-2, and (2) sociodemographic, behavioral, and health-related correlates of infection. HSV-1 seroprevalence was three times higher than HSV-2. HSV-2 seropositivity was significantly associated with HIV-positive status, lower income, greater frequency of anal insertive sex, and marginalized racial identities. Similarly, HSV-1 + HSV-2 coinfection was related to HIV-positive status, low to moderate income, and non-Hispanic/Latino Black or Mixed race/ethnicity. HIV status emerged as the strongest independent risk factor for both HSV-2 and HSV-1 + HSV-2 infection, and after adjusting for confounders. These findings highlight that HSV risk is shaped by intersecting behavioral, social, and structural factors, not just individual sex behaviors, and that STI conditions are syndemic. Future research should explore the mechanisms linking HIV to HSV-1 and HSV-2 among MSM, with attention to health risks influenced by social and structural determinants.