The COVID-19 pandemic highlighted the importance of effective communication to build and strengthen public trust in the field of public health. To address this need, we conducted virtual qualitative message testing via focus groups and individual in-depth interviews with a demographically and psychographically diverse mix of 100 English-speaking U.S. adults in March and April 2024. Following best practices in health literacy and plain language, we developed and tested 20 primary messages that focused on core values of the public health field and public health activities. Throughout message testing, participants demonstrated an unexpectedly limited or inaccurate understanding of public health, which shaped their reactions to messages. Although participants expressed positive reactions to some aspects of messages that humanize public health professionals, reflect audiences' lived experiences, provide clear and specific examples of public health activities, and highlight public health efforts within a local context, their limited or inaccurate understanding of public health made it difficult to assess message efficacy and resonance. After participants reviewed the messages, researchers observed that participants exhibited negligible shifts in their trust in the public health field and perceptions of its value and still had trouble articulating core public health concepts. Findings reveal substantial information gaps related to public health - that is, what public health is, what public health professionals do, and how it impacts lives and communities - and provide new insights about public health literacy and opportunities for developing effective messaging strategies about the public health field.
Keywords: Public health; communication; credibility; focus group; in-depth interview; messaging; segmentation; trust; understanding; value.