Background and Objective:
An essential element of managing a public health emergency is communication. The rise in popularity of YouTube videos about Emergency Use Authorization (EUA) matched the announcement of the first Covid-19 vaccine receiving an EUA. EUA communication by public health authorities coincided with social media messaging by individuals, some of whom amassed vast global audiences. We aim to analyze the EUA policy from the perspective of the 1) influencer, Dr. John Campbell, a U.K.-based nurse educator and popular YouTuber and 2) his global audience of social media users who watched Campbell’s EUA-related videos 4.5M times, posting 38,000 comments.

Methods:
We used descriptive statistics, content analysis, computational linguistics, and natural language processing in VOSviewer to analyze Campbell’s video messages and YouTube statistics; 38,000 comments to his 5 videos about EUA; and audience engagement – likes and comments per video view. Video transcripts and audience comments were transformed into term networks that explain the main discussion topics by visualizing co-occurring terms.

Results:
By November 2022, Campbell’s 2.56M subscribers represented 0.03% of the global population. The YouTube videos about EUAs he uploaded in Nov 2020-September 2022 demonstrate high audience engagement. Campbell’s YouTube follower comments provide evidence of social media users’ concerns with how EUAs are used, especially late in the pandemic. There is disagreement about the meaning and application of EUA. Some commenters question if the emergency continues to exist, challenge the process of granting EUAs, and question motivations by pharmaceutical companies and public health authorities. EUA comments are linked to other Covid-19 discussions, which we explain in depth.

Conclusion:
While not without controversy, Campbell’s messages invite participatory dialogue and broad audience engagement. This case study offers insight about how the influencer engages the audience and how the audience responds, each with implications for health communication, health administration, and health policy.