BackgroundImproving confidence in and uptake of COVID-19 vaccines and boosters among long-term care workers (LTCWs) is a crucial public health goal, given their role in the care of elderly people and people at risk. While difficult to reach with workplace communication interventions, most LTCWs regularly use social media and smartphones. Various social media interventions have improved attitudes and uptake for other vaccines and hold promise for the LTCW population.ObjectiveWe aimed to develop a curated social web application (interactive website) to increase COVID-19 vaccine confidence (a 3-arm randomized trial is underway).MethodsFollowing user-centric design and participatory research approaches, we undertook the following 3 steps: (1) content identification, (2) platform development, and (3) community building. A LTCW and stakeholder advisory group provided iterative input. For content identification (step 1), we identified topics of concern about COVID-19 vaccines via desktop research (published literature, public opinion polls, and social media monitoring), refined by interviewing and polling LTCWs. We also conducted a national online panel survey. We curated and fact-checked posts from popular social media platforms that addressed the identified concerns. During platform development (step 2), we solicited preferences for design and functionality via interviews and user experience testing with LTCWs. We also identified best practices for online community building (step 3).ResultsIn the interviews (n=9), we identified 3 themes: (1) LTCWs are proud of their work but feel undervalued; (2) LTCWs have varying levels of trust in COVID-19–related information; and (3) LTCWs would welcome a curated COVID-19 resource that is easy to understand and use-"something for us". Through desktop research, LTCW interviews, and our national online panel survey (n=592) we found that participants are interested in information about COVID-19 in general, vaccine benefits, vaccine risks, and vaccine development. Content identification resulted in 434 posts addressing these topic areas, with 209 uploaded to the final web application. Our LTCW poll (n=8) revealed preferences for personal stories and video content. The platform we developed is an accessible WordPress-based social media web application, refined through formal (n=3) and informal user experience testing. Users can sort posts by topic or subtopic and react to or comment on posts. To build an online community, we recruited 3 LTCW “community ambassadors” and instructed them to encourage discussion, acknowledge concerns, and offer factual information on COVID-19 vaccines. We also set “community standards” for the web application.ConclusionsAn iterative, user-centric, participatory approach led to the launch of an accessible social media web application with curated content for COVID-19 vaccines targeting LTCWs in the United States. Through our trial, we will determine if this approach successfully improves vaccine confidence. If so, a similar social media resource could be used to develop curated social media interventions in other populations and with other public health goals.