Responding to Emerging Epidemics: Insights From Stakeholders on Mpox Vaccine Rollout in Philadelphia.

Background: The 2022 mpox outbreak serves as an important example of a rapidly emerging epidemic that disproportionately affected marginalized populations. Despite the availability of a preventive vaccine, its deployment ultimately fell short of reaching the populations at greatest risk. Therefore, we sought to evaluate the vaccination campaign from the perspectives of key stakeholders. Methods: We conducted semistructured interviews to assess knowledge and perceptions of mpox, as well as barriers and facilitators to vaccine uptake in Philadelphia. We recruited health care clients and community members who were eligible for mpox vaccination and health care workers and community-based organization staff involved in vaccination efforts. We used purposeful selection to ensure inclusion of people with HIV. We used an integrated analysis approach that combined modified grounded theory and implementation science constructs. Results: We interviewed 21 health care clients, 9 community members, 10 health care workers, and 3 community-based organization staff after the primary mpox response in 2022 between February 2023 and October 2024. Participants varied in their knowledge and perceptions of mpox risk, primarily varying based on the perceived importance of sexual identity vs sexual behaviors. They generally believed that at-risk individuals should be vaccinated. Participants reported trusting mpox information from sources they trusted for other health information, such as health departments or knowledgeable members of social networks. Most participants expressed concern about inequitable distribution of the vaccine. Commonly reported facilitators to vaccination included one's own risk perception, technological literacy, co-locating vaccinations with existing clinical and social spaces, and outreach through trusted health-, community-, and social network-based resources. Knowledge, administrative (eg, difficulty signing up), and logistical (eg, limited clinic hours) barriers to vaccine access were thought to exacerbate inequities. Conclusions: While an effective mpox vaccine was a key asset in the response, barriers related to availability, accessibility, awareness, and logistical constraints limited its reach to those at highest risk.