The spread of misinformation on the internet regarding the COVID-19 pandemic, such as unproven or fake cures, has been a serious concern. However, the extent to which social media usage affects individuals' health behavior, particularly when reliable information is scarce, is not well understood. This study evaluates the impact of social media usage on individuals’ responses to the COVID-19 pandemic, such as demand for necessities and social distancing. We conduct an original online survey of 1804 Japanese respondents in March 2020. Japan is suitable because it confirmed COVID-19 cases earlier than most other countries. Scientific evidence about the coronavirus and protective measures was scarce in the initial pandemic phase, despite the spread of unconfirmed rumors. Our analysis focuses on the usage of Twitter, Facebook, and Instagram. We use the entropy balancing method to control for heterogeneity in observed characteristics between social media users and non-users. The results show that while users are more likely to maintain social distancing practices, they are also more likely to take measures whose reliability is not scientifically confirmed, such as eating fermented soybeans. Although previous studies emphasize the negative effects of social media, our results suggest that it has both bright and dark sides.

关于 COVID-19 大流行的错误信息在互联网上的传播，例如未经证实或虚假的治疗方法，一直是一个严重的问题。然而，社交媒体的使用对个人健康行为的影响程度尚不清楚，尤其是在可靠信息匮乏的情况下。这项研究评估了社交媒体的使用对个人对 COVID-19 大流行的反应的影响，例如对必需品的需求和社会距离。我们在 2020 年 3 月对 1804 名日本受访者进行了一项原始在线调查。日本是合适的，因为它比大多数其他国家更早确认了 COVID-19 病例。尽管有未经证实的谣言传播，但在大流行初期，关于冠状病毒和保护措施的科学证据很少。我们的分析侧重于 Twitter、Facebook 和 Instagram 的使用情况。我们使用熵平衡方法来控制社交媒体用户和非用户之间观察到的特征的异质性。结果表明，虽然用户更有可能保持社交距离，但他们也更有可能采取可靠性未经科学证实的措施，例如食用发酵大豆。尽管之前的研究强调了社交媒体的负面影响，但我们的结果表明它既有光明的一面，也有黑暗的一面。