This study applies the difference-in-difference method on panel data collected from internet surveys to investigate changes in the preventive behaviors and mental health of individuals as influenced by the COVID-19 state of emergency declaration between March and June 2020. The key findings are: (1) The declaration led people to exhibit preventive behaviors but also generated negative emotions; (2) Such behaviors persisted even after deregulation of the state of emergency; (3) Making the declaration early (vs. late) had a larger effect on preventive behavior, with the gap between residents’ behaviors for areas that made early vs. late declarations persisting after the deregulation; and (4) The effects on mental health diminished during the state of emergency and disappeared after its deregulation.

本研究对从互联网调查中收集的面板数据应用差分法，调查 2020 年 3 月至 2020 年 6 月期间受 COVID-19 紧急状态声明影响的个人预防行为和心理健康的变化。主要发现是: (1) 该宣言导致人们表现出预防行为，但也产生了负面情绪；(2) 这种行为即使在解除紧急状态后仍然存在；(3) 早申报（vs 晚申报）对预防行为的影响更大，早申报地区与晚申报地区的居民行为差异在放松管制后仍然存在；(4) 对心理健康的影响在紧急状态期间减弱，在解除管制后消失。