Digital Dissemination Strategies for Health Promotion Videos in Indigenous Communities in California: Protocol for a Three-Arm Comparative Study.

Background: Despite the availability of effective vaccines, flu and COVID-19 uptake remains suboptimal, including among Indigenous communities in California who face unique barriers to accessing public health information. While previous research has evaluated health communication message content and design, fewer studies have systematically compared different dissemination strategies for the same intervention, leaving gaps in understanding optimal approaches for reaching marginalized populations. Objective: This protocol describes a three-arm dissemination study designed to compare the effectiveness of different strategies for distributing COVID-19 and flu vaccine promotion videos among Indigenous Peoples residing in California, including American Indian and Alaska Natives, and migrant Indigenous Peoples from Latin America. Methods: Following extensive formative work, including cross-sectional surveys, social network analyses, a discrete choice experiment, and qualitative focus groups conducted with guidance from an Indigenous Community Advisory Board, we developed four 30-second vaccine promotion videos available in English and Spanish, two targeting American Indian and Alaska Native communities and 2 targeting Latin American communities. Videos will be translated to four Indigenous languages (Purépecha, Mam, Zapoteco, and Mixteco). The study compared three dissemination strategies implemented over a two-month period: (1) targeted social media advertisements on Facebook and Instagram, (2) distribution through community-based organizations using their established communication channels, and (3) peer-to-peer sharing through Indigenous community members ("seeds") recruited from previous research. Primary outcomes focus on dissemination effectiveness, defined by measures of reach (eg, link shares, clicks and video views), engagement (eg, watch time and survey completion), and message impact (eg, trust in the message and vaccination intent), assessed using Bitly link tracking, YouTube analytics, and follow-up surveys. Descriptive and comparative analyses will be conducted to assess differences across dissemination strategies. Results: The study was funded in January 2023. Intervention development was completed in July 2025. Dissemination activities and data collection across all three study arms were conducted between October 6, 2025, to November 28, 2025, aligned with the COVID-19 and influenza vaccination season in the United States. Data consolidation, cleaning, and analyses began January 2026 and primary results are expected to be submitted for publication in Spring 2026. Conclusions: This study addresses a critical gap in health communication research by providing a systematic methodology for comparing digital dissemination strategies within Indigenous communities. The combination of community-informed recruitment, multilingual accessibility, and comprehensive digital tracking tools offers a replicable model for evaluating how public health messages spread through different channels, particularly for populations historically excluded from traditional outreach efforts.