JMIR Publications

ABSTRACT

Background:

The unprecedented speed of COVID-19 vaccine development and approval has raised public concern about its safety. However, studies on public discourses and opinions on social media focusing on COVID-19 vaccine adverse events (AEs) are rare.

Objective:

In this study, we analyzed Korean tweets about the COVID-19 vaccines (Pfizer, Moderna, AstraZeneca, Janssen, and Novavax) after the vaccine rollout. We aimed to explore the topics and sentiments of tweets about COVID-19 vaccines and examine their changes over time. We also analyzed topics and sentiments focused on AEs related to vaccination using only tweets with terms about AEs.

Methods:

We devised a sophisticated methodology consisting of five steps: keyword search on Twitter, data collection, data preprocessing, data analysis, and result visualization. We used the Twitter REST API for data collection. A total of 1,659,158 tweets were collected from February 1, 2021, to March 31, 2022. Finally, 165984 data points were analyzed after excluding retweets, news, official announcements, advertisements, duplicates, and tweets with less than two words. We applied a variety of preprocessing techniques that are suitable for the Korean language. We ran a suite of analyses using various Python packages: latent Dirichlet allocation (LDA), hierarchical LDA, and sentiment analysis.

Results:

The topics about the COVID-19 vaccines have a very large spectrum, including vaccine-related AEs, emotional reactions to vaccination, vaccine development and supply, and government vaccination policies. Among them, the top major topic was AEs related to COVID-19 vaccination. The AEs ranged from the adverse reactions listed in the safety profile (e.g., myalgia, fever, fatigue, injection site pain, myocarditis/pericarditis, and thrombosis) to unlisted reactions (e.g., irregular menstruation, changes in appetite and sleep, leukemia, and deaths). Our results showed a notable difference in the topics for each vaccine brand. The topics pertaining to the Pfizer vaccine mainly mentioned AEs. Negative public opinion has prevailed since the early stages of vaccination. In the sentiment analysis based on vaccine brand, the topics related to the Pfizer vaccine expressed the strongest negative sentiment.

Conclusions:

Considering the discrepancy between academic evidence and public opinions related to COVID-19 vaccination, the government should provide accurate information and education. Furthermore, our study suggests the need for management to correct the misinformation related to vaccine-related AEs, especially affecting negative sentiment. This study provides valuable insights into public discourses and opinions regarding the COVID-19 vaccination.