Supplementary information on the data and methods.

This includes data collection considerations (incl. hashtags), analysis of bots in the dataset, biases in data, classification tasks, and structural break analyses. (ZIP)</p

Changes in absolute numbers of retweets, expressed in 1000s of tweets, with ratio in parentheses.

Changes in absolute numbers of retweets, expressed in 1000s of tweets, with ratio in parentheses.</p

Visualisation of the retweet networks before and after the WHO declaration, color-coded by community.

Visualisation of the retweet networks before and after the WHO declaration, color-coded by community.</p

Significant VAR coefficients for the simple lag-1 model.

The left side shows the raw coefficients, the right side shows the log-normalized influence taking into account total influence of each group (see text for details).</p

Dendrogram for custom MFT virtue dictionaries.

Dendrogram for custom MFT virtue dictionaries.</p

Changes on selected LIWC components pre- and post-declaration.

X axis shows top 15 absolute score changes. Y axis shows percentage of max pre/post score. Arrow shows direction of change.</p

Daily word count by community.

WHO pandemic declaration at the center.</p

Dendrogram for LIWC-Specific content.

Dendrogram for LIWC-Specific content.</p

Dendrogram showing hierarchical clustering for pre- and post-declaration tf-idf vectors.

Dendrogram showing hierarchical clustering for pre- and post-declaration tf-idf vectors.</p