中文摘要
本文构建了一个传染病经济学—流行病学模型，其中个体可能多次感染，且个体主体对社交距离与疫苗接种做出内生选择。任何一个人采取的防护行动都会降低其他人未来面临的感染风险。这些行为所具有的正外部性为疫苗补贴与社交距离补贴提供了政策依据，但对一种防护行动进行补贴会削弱个体采取其他防护行动的激励。疫苗补贴会提高疫苗接种率，并降低稳态感染流行度；而社交距离补贴既可能提高、也可能降低稳态感染流行度。（JEL D62, D91, I12, I18）
Abstract
This paper analyzes an economic-epidemiological model of infectious disease where it is possible to become infected more than once and individual agents make endogenous choices of social distancing and vaccine adoption. Protective actions adopted by any one person reduce future risks to other people. The positive externalities associated with these behaviors provide motivation for vaccine and social-distancing subsidies, but subsidizing one protective action reduces incentives for other protective actions. A vaccine subsidy increases vaccine adoption and reduces steady-state infection prevalence; a social distancing subsidy can either increase or reduce steady-state infection prevalence. (JEL D62, D91, I12, I18)