Worldwide, nearly one million new sexually transmitted infections (STIs) occur daily. Viral hepatitis caused by the hepatitis A (HAV), B (HBV), and C (HCV) viruses represent a major public health issue and are considered STIs, primarily associated with unprotected sexual intercourse among men who have sex with men (MSM). Hepatitis A is globally prevalent, with approximately 1.4 million cases annually, and outbreaks among MSM populations have been reported in recent years. This study aimed to analyze the prevalence of HAV seropositivity and vaccination opportunities among PrEP (Pre-Exposure Prophylaxis) users attending an HIV/STI reference center.

Cross-sectional study using data from individuals who sought PrEP between 08/2022 and 08/2024. Data were entered into the REDCap platform, approved by the ethics committee, and analyzed using STATA/MP 19. The prevalence of HAV positivity and its possible associated factors were calculated. The strength of association was estimated using the prevalence ratio (PR) with 95% confidence intervals (95% CI). Variables showing significant association in the bivariate analysis were included in a Poisson regression model with robust variance.

A total of 502 PrEP prescriptions were recorded during the study period; 393 (78%) were cisgender men, 357 (71%) MSM, with a mean age of 29 years. The HAV seroprevalence was 48% (95% CI: 43–52). In the multivariate analysis, HAV prevalence was significantly higher among individuals aged ≥ 40 years (PR: 2.1; 95% CI: 1.5–2.9; p < 0.001) and among those with previous use of PEP (post-exposure prophylaxis) (PR: 1.3; 95% CI: 1.0–1.6; p = 0.015). The median follow-up time was 313 days (IQR: 158–511), with four new cases of hepatitis A identified, corresponding to an incidence rate of 8.6/1,000 person-years (95% CI: 3.2–23). Among 250 (49.8%) individuals susceptible to HAV, 182 (78%) were referred for vaccination, but only 9% (95% CI: 5.5–14.5) received at least one dose.

Hepatitis A is a frequent, vaccine-preventable infection among MSM populations. In this study, we observed a high susceptibility to HAV, particularly among younger MSM. Follow-up within PrEP programs represents an opportunity to recommend immunization. Following the implementation of Technical Note No. 184/2025 – DPNI/DATHI/SVSA/MS, which provides HAV vaccination for PrEP users through the Brazilian public health system (SUS), we expect to achieve broader vaccination coverage and a positive epidemiological impact with reduced incidence of new cases.