Background: Long-acting injectable cabotegravir (CAB-LA) for preexposure prophylaxis (PrEP) has proven efficacious in randomized controlled trials. Further research is critical to evaluate its effectiveness in real-world settings and identify effective implementation approaches, especially among young sexual and gender minorities (SGMs).

Objective: ImPrEP CAB Brasil is an implementation study aiming to generate critical evidence on the feasibility, acceptability, and effectiveness of incorporating CAB-LA into the existing public health oral PrEP services in 6 Brazilian cities. It will also evaluate a mobile health (mHealth) education and decision support tool, digital injection appointment reminders, and the facilitators of and barriers to integrating CAB-LA into the existing services.

Methods: This type-2 hybrid implementation-effectiveness study includes formative work, qualitative assessments, and clinical steps 1 to 4. For formative work, we will use participatory design methods to develop an initial CAB-LA implementation package and process mapping at each site to facilitate optimal client flow. SGMs aged 18 to 30 years arriving at a study clinic interested in PrEP (naive) will be invited for step 1. Individuals who tested HIV negative will receive mHealth intervention and standard of care (SOC) counseling or SOC for PrEP choice (oral or CAB-LA). Participants interested in CAB-LA will be invited for step 2, and those with undetectable HIV viral load will receive same-day CAB-LA injection and will be randomized to receive digital appointment reminders or SOC. Clinical appointments and CAB-LA injection are scheduled after 1 month and every 2 months thereafter (25-month follow-up). Participants will be invited to a 1-year follow-up to step 3 if they decide to change to oral PrEP or discontinue CAB-LA and to step 4 if diagnosed with HIV during the study. Outcomes of interest include PrEP acceptability, choice, effectiveness, implementation, and feasibility. HIV incidence in the CAB-LA cohort (n=1200) will be compared with that in a similar oral PrEP cohort from the public health system. The effectiveness of the mHealth and digital interventions will be assessed using interrupted time series analysis and logistic mixed models, respectively.

Results: During the third and fourth quarters of 2022, we obtained regulatory approvals; programmed data entry and management systems; trained sites; and performed community consultancy and formative work. Study enrollment is programmed for the second quarter of 2023.

Conclusions: ImPrEP CAB Brasil is the first study to evaluate CAB-LA PrEP implementation in Latin America, one of the regions where PrEP scale-up is most needed. This study will be fundamental to designing programmatic strategies for implementing and scaling up feasible, equitable, cost-effective, sustainable, and comprehensive alternatives for PrEP programs. It will also contribute to maximizing the impact of a public health approach to reducing HIV incidence among SGMs in Brazil and other countries in the Global South.

Trial registration: Clinicaltrials.gov NCT05515770; https://clinicaltrials.gov/ct2/show/NCT05515770.

International registered report identifier (irrid): PRR1-10.2196/44961.