  This study investigates the use of causal narratives in public social media
communications by U.S. public agencies over the first fifteen months of the
COVID-19 pandemic. We extract causal narratives in the form of cause/effect
pairs from official communications, analyzing the resulting semantic network to
understand the structure and dependencies among concepts within agency
discourse and the evolution of that discourse over time. We show that although
the semantic network of causally-linked claims is complex and dynamic, there is
considerable consistency across agencies in their causal assertions. We also
show that the position of concepts within the structure of causal discourse has
a significant impact on message retransmission net of controls, an important
engagement outcome.
