Fascinating analysis of nearly 100 million Facebook users expressing views about vaccines. I will do my best to summarize the authors' findings, as I understand them. THREAD. (Paper: https://www.nature.com/articles/s41586-020-2281-1)

Antivaccination clusters are smaller in terms of numbers but they are quite central in the overall network because they are deeply entangled with the "undecided" clusters.

This means that the pro-vaccine people on Facebook "may remain ignorant of the main conflict and have the wrong impression that they are winning."

Based on this analysis, the "undecided" clusters are not passive; they are actually highly active in the discussion.

The antivaccination clusters offer a diversity of narratives surrounding vaccines (their safety, conspiracy theories, alt med suggestions), whereas the provaccine views are more "monothematic."

Antivaccination clusters also show the highest growth during the 2019 measles outbreak. The authors hypothesize that it may be because they offer a diversity of narratives that can reach more people.

Medium-sized antivaxx clusters grow the most. Pro-vaccination folks may notice the big antivaxx accounts, but the smaller ones, which grow the most, can go unnoticed.

All in all, a sobering analysis. I hope these data can be used to help inform vaccine messaging in the near future. Because, with COVID-19, we've got a potentially huge problem on the horizon....