PROJECT SUMMARY The U.S. experience with COVD-19 vaccination has shown that an individual's decision to vaccinate stems from many factors, including beliefs related to vaccine safety1; the norms of family, peers, and community2,3; media sources4; and federal, state, and local policy5,6. Many of these factors stem from a historical evolution and regional idiosyncrasies, including regional differences in vaccination exemptions, levels of state funding, public health communications, religious and political sentiments, and, often, longstanding reluctance to vaccinate. Although there is evidence that these factors contribute to vaccination in several domains, no past research has examined the ecology of this evolution for any vaccine. As a result, if a new HIV vaccine were introduced in the near future, comprehensive, rigorous knowledge about the impact of vaccine factors, information circulating in the community, norms, and public health policies would be paramount. This project will investigate the interplay of these ecological factors at the state or county level, to predict over-time changes in individual intentions to vaccinate against HIV if a vaccine were approved, as well as individual vaccination against other diseases such as influenza, Hepatitis A, and COVID-19 among Men Who Have Sex with Men (MSM). The project will study the impact of the ecology of vaccination on a future HIV vaccine by linking longitudinal surveys of diverse MSM (N = 1500) to state/county/zip code data on community-based vaccine information in the media, vaccination norms, as well as vaccine and HIV policy, including LGBT friendly policies and public health communications in the media. After understanding key factors affecting HIV vaccination intentions, we will conduct an experiment with another sample of diverse MSM (N = 1,000; Aim 2). Participants will be randomized to conditions of different vaccine characteristics, information in the community, vaccination norms, and public health policies, and then complete measures of vaccine choices and intentions; the choice to enroll in a vaccination trial registry and the choice to sign up for an educational session about HIV-vaccine science as the behavioral endpoints for our experiment. Participants will also complete measures of behavioral control, attitudes, and subjective norms as the possible mediators of effects of our choice and intention outcomes. The project will be informed by extensive pilot data on vaccine policy, public health communications about vaccines and HIV, and vaccine misinformation across states and over time, as well as experience recruiting and managing cohorts of MSM and investigating the acceptability of an HIV vaccine in this population. The team includes expertise in public health, psychology, HIV medicine and HIV vaccine trials, communication, public policy, and economics, and will leverage the resources of the University of Pennsylvania, the HIV Vaccine Trials Network (HVTN), the Penn CFAR, and the Annenberg Public Policy Center (APPC) to conduct cutting edge research about the determinants of vaccination against HIV. The data obtained from this innovative project will supply the evidence base to inform policies and public health communications to promote a future HIV vaccine and other recommended vaccines among MSM.

PROJECT NARRATIVE This project will investigate the influence of vaccine characteristics, information in the community, vaccination norms, and public health policies on the intention to receive an HIV vaccine should it be approved. It will inform vaccination policy and communications more generally with respect to other adolescent and adult vaccines.