From the CDC to emerging infectious disease publics: The long-now of polarizing and complex health crises

As the COVID-19 pandemic evolved, the Center for Disease Control and Prevention used Twitter to share updates about the virus and safety guidelines, reaching millions instantly, in what we call the CDC public. We analyze two years of tweets, from, to, and about the CDC using a mixed-methods approach to characterize the nature and credibility of COVID-19 discourse and audience engagement. We found that the CDC is not engaging in two-way communication with the CDC publics and that discussions about COVID-19 reflected societal divisions and political polarization. We introduce a crisis message journey concept showing how the CDC public responds to the changing nature of the crisis (e.g., new variants) using ``receipts'' of earlier, and at times contradictory, guidelines. We propose design recommendations to support the CDC in tailoring messages to specific users and publics (e.g., users interested in racial equity) and in managing misinformation, especially in reaction to crisis flashpoints.