Vaccination Coverage and Prevention Counselling for Vaccine-Preventable STIs Among HIV PrEP Users in São Paulo,...

HIV pre-exposure prophylaxis (PrEP) users may be disproportionately vulnerable to sexually transmitted infections (STIs) in general, including several that are vaccine-preventable. Understanding immunization patterns in this population is, therefore, crucial. However, data on vaccination coverage among Brazilian PrEP users remains limited.

We conducted a retrospective single-centre study of adults using HIV PrEP at an STI clinic in São Paulo, Brazil, between 2017 and 2024, to assess vaccination adequacy for vaccine-preventable STIs among PrEP users, as well as other STI prevention measures during follow-up. Demographic characteristics, substance use, STI history and vaccination status for hepatitis A (HAV), hepatitis B (HBV), human papillomavirus (HPV) and MPox were extracted from medical records, immunization registries and laboratory results, and descriptive analyses were performed.

Among 190 participants (median age: 36 years), 89.5% were gay or other men who have sex with men (MSM). Over a mean follow-up period of 45 months, complete vaccination coverage was observed in 97.7% for HBV, 49.5% for HAV, 24.2% for HPV and 1.6% for MPox. Despite documented prior vaccination, a proportion of participants remained susceptible to HAV (16.3%) and HBV (2.3%). Furthermore, a substantial proportion of participants (32.1% for HAV, 53.7% for HPV and 81.0% for MPox) had neither a documented vaccination status nor a provider recommendation for vaccination recorded in their medical charts. HPV- and MPox-related clinical lesions were documented in 17.9% and 2.1% of participants, respectively.

Notable gaps in immunization against preventable STIs were observed in this PrEP cohort in São Paulo, Brazil. While HBV coverage was high, uptake of HAV, HPV and MPox vaccines was low. Addressing these gaps in our cohort requires transitioning from mere provider recommendations to structural public health policies. Implementing on-site vaccine administration within PrEP services, integrating immunization into STI screening, expanding free access and addressing key vulnerabilities are critical steps to eliminate structural barriers and reduce the STI burden.