Clinical trials

This study aims to improve access to HIV prevention using pre-exposure prophylaxis (PrEP) among underserved populations in Rio de Janeiro, including gay and bisexual men, transgender women, and sex workers. Despite the proven effectiveness of PrEP, many people at higher risk of HIV face barriers to accessing and continuing this prevention method, especially those living in socially and economically vulnerable communities. The study will evaluate whether offering PrEP directly in community-based settings-such as non-governmental organizations, mobile health units, and through telehealth and digital tools-can increase its uptake and continued use. Participants who test negative for HIV will be offered daily oral PrEP, along with counseling and follow-up support. Those who test positive will be referred for appropriate treatment. The main hypothesis is that delivering PrEP in community settings, combined with supportive strategies like mobile health interventions, will be feasible, acceptable, and more effective in reaching and engaging vulnerable populations, ultimately helping to reduce new HIV infections.

The goal of this clinical trial is to learn if doxycycline post-exposure prophylaxis (doxy-PEP) can help prevent bacterial sexually transmitted infections (STIs) among sexual and gender minorities in Rio de Janeiro, Brazil, including men who have sex with men, transgender women, and travestis who are living with HIV or using HIV pre-exposure prophylaxis (PrEP). Bacterial STIs such as syphilis, gonorrhea, and chlamydia remain common in these populations, even with existing prevention strategies. This study aims to answer the following questions: whether doxy-PEP can reduce the number of new STIs, whether it is safe and well tolerated, whether participants use it as recommended, and whether its use may contribute to antibiotic resistance or changes in the body's natural bacteria. Doxy-PEP involves taking a dose of doxycycline, an antibiotic, shortly after sexual activity to reduce the risk of acquiring STIs. Participants will first receive information and counseling about doxy-PEP, including its possible benefits and risks, and will then choose whether or not to use this prevention strategy. Those who choose to use doxy-PEP will take doxycycline after sex as instructed and will be followed for up to 48 weeks, with clinic visits approximately every three months. During these visits, participants will be tested for STIs, monitored for side effects, and asked about medication use, sexual health, and overall well-being. Researchers will collect information on new STI diagnoses, safety, and how consistently participants use doxy-PEP. The study will also explore participants' experiences and perceptions of this strategy. The results of this study will help determine whether doxy-PEP is a practical and acceptable approach for STI prevention in Brazil and may inform future public health strategies.

The goal of this study is to learn how well long-acting lenacapavir works to prevent human immunodeficiency virus (HIV) infection in people at higher risk of getting HIV in Brazil. The study will also learn about safety, continued use over time, and whether people prefer this option compared to daily oral pre- exposure prophylaxis (PrEP). The main questions it aims to answer are: How many participants get HIV while using long-acting lenacapavir? How safe is long-acting lenacapavir in real-world health services? How many participants continue using their chosen prevention method over time? What factors help or make it harder for participants to stay on prevention? Researchers will compare two HIV prevention options to understand how they work in routine care: Long-acting lenacapavir, given as an injection under the skin every 6 months, Daily oral pre-exposure prophylaxis (PrEP), taken as a pill containing tenofovir disoproxil fumarate and emtricitabine, Participants will choose the prevention option they prefer after receiving counseling. This is not a randomized study. Researchers will follow participants for up to 2 years. Participants will: Receive either an injection every 6 months or take a daily pill, Visit the clinic regularly for HIV testing and health checkups, Receive testing and treatment for sexually transmitted infections, Answer questions about their health, medication use, and experiences, Receive prevention counseling and condoms. This study will help health services understand how to offer long-acting HIV prevention in Brazil and how to better support people who want to prevent HIV infection.

Phase 4 study to evaluate the immunogenicity and Safety of the 17DD Yellow Fever vaccine in HIV infected individuals, compared to non-HIV-infected individuals. Main objective: To compare the proportion of seroconversion and the geometric mean of neutralizing antibodies 30 days and 365 days after vaccine. Secondary objectives: To evaluate whether the titles of neutralizing antibodies are associated with CD4 lymphocyte counts, CD8 lymphocyte counts, CD4 nadir, HIV viral load and use of antiretroviral therapy. To assess the yellow fever vaccine viremia at day 10 after vaccine.To compare the incidence of adverse events in HIV-infected and non-HIV-infected individuals.