PROJECT SUMMARY/ABSTRACT Approximately 80 million people in the United States – or about one in four – are infected with human papillomavirus (HPV). HPV can cause cancer and there are vaccines that protect against cancer-related strains. Evidence supporting vaccine efficacy and safety is robust, and vaccine availability is widespread; however coverage rates continue to fall short of the national goal of 80% (48.6% in 2017). Understanding the barriers to vaccine acceptance, particularly related to parent resistance and their informational needs, is key to strengthening vaccine uptake among adolescents. Communicating evidence to parents and engaging them through narrative strategies may address some of the barriers during the decision-making process. Parents use social media as an important parenting tool and useful source for health information. In 2015, 75% of all parents used social media, and of these 1 in 4 used Twitter – equating to millions of parent users. We know that using social media data for surveillance has had early impact in public health. However, what is not known is the effectiveness of using large-scale social media data to inform a targeted social media intervention to support HPV vaccine uptake. This study will advance the growing field by evaluating the efficacy of an innovative narrative-focused intervention designed to communicate evidence and information about the HPV vaccine for parents who use social media as a health information source. The approach is informed by narrative engagement theory that posits narratives strengthen knowledge and promote engagement through storytelling by tapping into feelings of empathy, identification, and transportation. We will evaluate the efficacy of our Twitter-based pilot intervention in a randomized controlled trial that will enroll 600 parents/caregivers of children ages 9-14, whose child(ren) has not started the vaccine series. Our central hypothesis is that exposure to narrative-focused exemplar messages will lead to greater intention to vaccinate, and subsequently increased rates of vaccination in the intervention group compared to parents in the comparison group, who receive non-narrative HPV vaccine information (i.e., existing HPV vaccine information developed for Twitter). We will use a Twitter-based Community Advisory Board, virtual focus groups, and existing Twitter messages developed by the HPV Roundtable to inform narrative-focused message development. The proposed study will address three specific aims: 1) Develop narrative-focused scientific exemplars for HPV vaccine communication utilizing existing online messages and community engagement on Twitter; 2) Quantify differences in engagement, intention to vaccinate, and self-reported vaccination between parents exposed to the narrative-focused scientific exemplars and parents exposed to non-narrative scientific messages; 3) Collect and analyze longitudinal participant metadata to measure Twitter activity during the study peri...