This paper empirically tests Philip Strong's model of epidemic psychology, which posits three psycho-social epidemics (fear, moralization, and action) during disease outbreaks. Analyzing 122 million US tweets from 2020, the study identifies three phases in public response to COVID-19: refusal, anger, and acceptance. The refusal phase shows denial despite rising global death tolls; anger emerges after the first US death, marked by fear and resentment; acceptance follows the imposition of distancing measures, leading to a "new normal." Anger resurfaced cyclically with each surge in cases. The model's real-time operationalization allows its integration into epidemiological and mobility models.

Luca Maria Aiello, Daniele Quercia, Ke Zhou, Marios Constantinides, Sanja Šćepanović, Sagar Joglekar