News media has been utilized as a political tool to stray from facts,
presenting biased claims without evidence. Amid the COVID-19 pandemic,
politically biased news (PBN) has significantly undermined public trust in
vaccines, despite strong medical evidence supporting their efficacy. In this
paper, we analyze: (i) how inherent vaccine stances subtly influence
individuals' selection of news sources and participation in social media
discussions; and (ii) the impact of exposure to PBN on users' attitudes toward
vaccines. In doing so, we first curate a comprehensive dataset that connects
PBN with related social media discourse. Utilizing advanced deep learning and
causal inference techniques, we reveal distinct user behaviors between social
media groups with various vaccine stances. Moreover, we observe that
individuals with moderate stances, particularly the vaccine-hesitant majority,
are more vulnerable to the influence of PBN compared to those with extreme
views. Our findings provide critical insights to foster this line of research.

新闻媒体被用作政治工具，不依据事实提出有偏见的主张。在 COVID-19 大流行期间，政治偏见的新闻（PBN）在明显削弱公众对疫苗的信任，尽管有强有力的医学证据支持其功效。本文分析了以下两个方面：（i）疫苗态度如何潜移默化地影响个体选择新闻来源和参与社交媒体讨论；（ii）接触 PBN 对用户对疫苗态度的影响。我们首先整理了一个与社交媒体讨论相关的全面数据集，利用先进的深度学习和因果推理技术揭示了在具有不同疫苗态度的社交媒体群体之间存在着不同的用户行为。此外，我们观察到，相对于持极端观点的人群，持中立态度的个体（尤其是犹豫接种的大多数人）对 PBN 的影响更为脆弱。我们的研究结果为进一步推动这一研究领域提供了关键洞察。