The Federally Qualified Health Centers (FQHCs) in Wisconsin serve the most under-resourced communities in the state and are trusted sources in local communities. Although healthcare workers can be leveraged to champion COVID-19 vaccines, existing vaccine hesitancy among the FQHC workforce itself calls for research to identify promising messaging themes that can boost their vaccine confidence. In spring 2021, through a partnership with the Wisconsin Primary Health Association, we took a community-engaged approach to develop and field a survey including 46 beliefs (Ms = 1.36-4.25, SDs = 0.81-1.46, all on 5-point Likert scales) among employees of 10 out of the 17 FQHCs in Wisconsin. In total, 347 clinical team members and 349 non-clinical staff members (a) indicated their levels of (dis)agreement with all 46 belief items and (b) reported vaccine acceptance (dichotomized, acceptance = 77.6%) as well as recommendation intentions (dichotomized, yes = 73.9%). We carried out the Hornik & Woolf analyses in a multilevel logistic regression framework with bootstrapping to rank order all beliefs, segmented by subgroup and behavioral outcome. Our results suggest that communication-based interventions should promote beliefs such as those related to perceived safety and efficacy, rather than normative pressure from peers, while aiming to reduce doubts about information withholding and manipulation, the safety of the mRNA technology, the approval process, and "unnatural" ingredients in the vaccines. Subgroup-specific belief rankings are also provided. This study demonstrates the usefulness of incorporating the H&W approach into community-engaged research with local healthcare systems to improve health messaging for vaccine promotion.