BACKGROUND The potential of social media in promoting health has been widely demonstrated. However, research on the combination of social media and health campaigns in the Chinese context is limited. There is also a lack of a nationwide perspective on health campaigns. China's annual AIDS Week campaign, which uses social media for promotion, provides an opportunity for addressing this gap. OBJECTIVE This study aims to map the execution mechanism of China's AIDS Week policy and the characteristics of discussions by social media users in the five-year period of social context changes. The study extracts the progress and limitations of health campaigns in China over five years to provide a perspective for interventions in developing countries. METHODS This study uses the affordance perspective to map the discussions about AIDS on Weibo during the World AIDS Day week from November 29th to December 5th, from 2018 to 2021. Using the Latent Direct Allocation topic model, the study retrieves posts and extract key topics across the dataset. We then conducted sentiment analysis to classify expressed sentiments in the posts and performed temporal analysis to examine longitudinal trends in conjunction with the annual AIDS slogans and social environment. RESULTS After data cleaning, we retrieved 49,576 posts, 21 of the identified topics were coded and divided into 6 main themes: Response Methods, Specific Topics, Promotion, Virus Status, Specific Groups, and Positive Feedback. Chi-square tests revealed significant differences in sentiment distribution among themes in different years, but positive emotions were higher than negative emotions in the majority of years. Most posts did not receive any audience engagement. Additionally, audience engagement was influenced by the year's news hotspots, but not significantly correlated with the intensity or direction of sentiment. Temporal analysis revealed that news hotspots and social environment were the main factors influencing the distribution of discussion topics. CONCLUSIONS From 2018 to 2022, the health campaign during China's AIDS Week was designed to localize the WHO World AIDS Day. However, due to the limitations of the general public's awareness, political system, and social environment, Weibo has become a platform for reporting achievements to superiors rather than exchanging opinions with the audience. This has led to the formalization of the AIDS Week health campaign, which is highly efficient but has a limited impact. As the audience is greatly influenced by social hotspots, the execution of health campaigns should fully consider public opinion. Preachy promotion, under certain unofficial interpretations, may trigger panic and even rumors.

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