Code for: An Analytical Model of Behavior and Policy in an Epidemic

This paper examines the behavior of individuals susceptible to a deadly disease in a tractable equilibrium setting. We analytically characterize individually optimal mitigation behavior and the resulting equilibrium trajectory. Analysis is facilitated by a phase diagram. A key insight is that individually optimal behavior of those susceptible to the disease results in excessive caution. This behavior flattens the epidemic curve and prolongs the epidemic. In contrast, socially optimal behavior results in a higher infection rate, with a focus on minimizing cumulative deaths at minimum cost. The paper offers novel technical contributions and an improved understanding of externalities in econ-epi models.

本文在可处理的均衡框架下，分析了易感染致命疾病个体的行为特征。本文通过解析方法刻画了个体最优防疫行为及其对应的均衡演化轨迹，相位图的运用为分析提供了便利。核心研究洞见显示：易感个体的个体最优防疫行为会引发过度谨慎，此类行为虽会拉平疫情传播曲线，却同时延长了疫情持续时长。与之相对，社会最优防疫行为则会带来更高的感染率，其核心目标是以最低成本实现累计死亡人数的最小化。本文为经济-流行病（econ-epi）模型中的外部性问题提供了全新的技术贡献，并深化了学界对该类模型外部性的认知。