Modelling optimal lockdowns with waning immunity
研究了当疾病（如新冠）成为地方病且免疫可能失效时，长期持续最优封锁（或隔离）的建模问题，在动态一般均衡新古典增长框架中纳入疾病相关死亡率，并分析了封锁效果、居家办公生产率、死亡率及免疫衰退对最优限制的影响。
Abstract This paper studies continuing optimal lockdowns (can also be interpreted as quarantines or self-isolation) in the long run if a disease (Covid-19) is endemic and immunity can fail, that is, the disease has SIRS dynamics. We model how disease related mortality affects the optimal choices in a dynamic general equilibrium neoclassical growth framework. An extended welfare function that incorporates loss from mortality is used. In a disease endemic steady state, without this welfare loss even if there is continuing mortality, it is not optimal to impose even a partial lockdown. We characterize how the optimal restriction and equilibrium outcomes vary with the effectiveness of the lockdown, the productivity of working from home, the rate of mortality from the disease, and failure of immunity. We provide the sufficiency conditions for economic models with SIRS dynamics with disease related mortality–a class of models which are non-convex and have endogenous discounting so that no existing results are applicable.