JMIR Publications

ABSTRACT

Background:

Anti-vaccination views pervade online social media, fueling distrust in scientific expertise and increasing vaccine-hesitant individuals. While previous studies focused on specific countries, the COVID-19 pandemic brought the vaccination discourse worldwide, underpinning the need to tackle low-credible information flows on a global scale to design effective countermeasures.

Objective:

We quantify cross-border misinformation flows between users exposed to anti-vaccination (no-vax) content and the effects of content moderation on vaccine-related misinformation.

Methods:

To this aim, we collect 316 million vaccine-related Twitter messages in 18 languages, from October 2019 to March 2021. We geolocate users in 28 different countries and reconstruct a retweet network (RT) and a co-sharing network for each country. We identify communities of users exposed to no-vax content by detecting communities in the RT network via hierarchical clustering and manual annotation. We collect a list of low-credibility domains and quantify interactions and misinformation flows between no-vax communities of different countries.

Results:

We find that, during the pandemic, no-vax communities became more central in the country-specific debates and their cross-border connections strengthened, revealing a global Twitter anti-vaccination network. U.S. users are central in this network, while Russian users also become net exporters of misinformation during vaccination roll-out. Interestingly, we find that Twitter’s content moderation efforts, and in particular the suspension of users following the January 6th U.S. Capitol attack, had a worldwide impact in reducing misinformation spread about vaccines.

Conclusions:

These findings may help public health institutions and social media platforms to mitigate the spread of health-related, low-credible information by revealing vulnerable online communities.