How did Chinese public health authorities promote COVID-19 vaccination on social media? A content analysis of the vaccination promotion posts.

Objective: Drawing upon the health belief model, this study aims to analyze the message characteristics of coronavirus disease 2019 (COVID-19) vaccination promotion messages posted by influential Chinese public health institutions and how those characteristics affect audiences' participative engagement on Weibo, which is a popular social media site in China.

Methods: Two Chinese phrases for the COVID-19 vaccine were adopted as search terms to retrieve qualified posts on Weibo from 1 December 2019 to 18 March 2023. A total of 2546 posts by the top nine most impactful public health institutions were retained for quantitative content analysis.