Reddit Discussions During the 2022 Mpox Outbreak: Observational Analysis of Sentiment, Topics, and Audience...

Public health crises often reshape online discourse by amplifying uncertainty, frustration, stigma, and misinformation, with important implications for risk communication.

This study examines these dynamics on Reddit (Reddit Inc) during a recent outbreak, using Mpox as a case study.

We analyzed sentiment, topical themes, and audience engagement in posts and comments drawn from 4 Mpox-related subreddits. Using natural language processing methods, we applied sentiment analysis and latent Dirichlet allocation to classify 1169 posts and 6571 comments (from July 21, 2021, to July 16, 2025) into sentiment categories and 9 distinct topics. Of the 1169 posts, 611 (52.3%) were neutral, 370 (31.6%) were negative, and 188 (16.1%) were positive. Among comments, 2825 of 6571 (43%) were neutral, 1962 (29.9%) were negative, and 1784 (27.1%) were positive. We then used Kruskal-Wallis tests, Dunn post hoc comparisons, and Vargha-Delaney A to assess relationships among sentiment, topic, and engagement metrics.

Engagement differed significantly by sentiment (P<.001) and topic (P<.001). Negative posts had higher median scores (median 7, IQR 2-27) than positive ones (median 5, IQR 2-16; z score=6.02; adjusted P<.001; Vargha-Delaney A=0.55). Posts about systemic public health failures (Topic 4) received lower median scores (median 4, IQR 1.75-14.25) than other topics. Topic 9 accounted for 980 of 6571 (14.9%) comments, dominating discussions regardless of original post topic. Positive posts generated 284 of 922 (30.8%) positive comments, whereas negative posts received 526 of 1615 (32.6%) negative comments. Comments on positive posts had higher sentiment scores (Vargha-Delaney A=0.550), whereas comments on negative posts had lower sentiment scores (Vargha-Delaney A=0.463). Topic-level differences in comment sentiment were also observed: comments responding to posts on scientific- and policy-related debates (Topic 8) were more positive (Vargha-Delaney A=0.531), whereas those on systemic failures (Topic 4) were more negative (Vargha-Delaney A=0.478).

Overall, the findings highlight how audience reactions can amplify emotionally charged narratives and reframe technical information into socially and politically charged debates. These insights can inform public health communication strategies by anticipating likely audience responses, mitigating stigma and misinformation, and fostering constructive dialogue during health crises.