Hepatitis A (HAV), B (HBV), and C (HCV) remain major public-health concerns. HBV is vaccine-preventable, with universal and free immunization implemented in Brazil since 2016. Understanding the epidemiology and seroprevalence of these infections among users of HIV pre-exposure prophylaxis (PrEP) is crucial to develop strategies that expand vaccination coverage.

To assess the seroprevalence of HBV and HCV among PrEP users and identify associated factors.

Cross-sectional study including individuals who sought PrEP between 08/2022 and 08/2024. Data were entered into REDCap and analyzed using STATA/MP 19. Seroprevalence of HBV and HCV was determined by the positivity of Anti-HBs (with or without Anti-HBc) and total antibodies for HCV, respectively. Associated factors were evaluated using prevalence ratios (PR) and 95% confidence intervals (CI). Variables significant in bivariate analysis were included in a Poisson regression model with robust variance.

A total of 502 PrEP prescriptions were recorded: 249 (50%) White, 393 (78%) cisgender men, 357 (71%) men who have sex with men (MSM), mean age 29.5 years, 73 (15%) with prior PrEP use, 90 (19%) with prior PEP use, 136 (27%) reporting chemsex, and 269 (54%) with a history of STIs. Median follow-up time was 313 days (IQR: 158–511). Seroprevalence for HBV and HCV was 60.5% (302/499; 95% CI: 56.1–64.8) and 1% (5/500; 95% CI: 0.3–2.3), respectively, with only one case of active HCV (PCR-positive) and none of active HBV. In multivariate analysis, Anti-HBs prevalence was higher among individuals < 40 years (PR: 1.7; 95% CI: 1.2–2.3; p < 0.01) and those with a history of PEP (PR: 1.2; 95% CI: 1.0–1.4; p = 0.009). Anti-HBc antibody prevalence was 5.2% (95% CI: 3.4–7.6), associated with age ≥ 40 years (PR: 9.3; 95% CI: 3.19–57.99; p < 0.001) and transgender women/transvestite identity (PR: 8.7; 95% CI: 1.53–6.27; p = 0.002). Among those susceptible to HBV, 196 (39%) were referred for vaccination and 147 (75%) received at least one dose, yielding a vaccination coverage of 41% (95% CI: 32.8–49.2).

Continuous assessment of the serological profile for hepatitis among PrEP users is essential. Periodic review of HBV vaccination status is recommended, particularly for transgender individuals and those ≥ 40 years, who showed lower vaccination coverage, possibly due to unawareness of the vaccine’s wide availability. Such measures are fundamental to reducing HBV incidence.