Negative infectious disease externalities are less prevalent in the absence of government intervention and less costly to society than is often supposed. That is so for three reasons. (1) Unlike externality‐creating behaviors in many classical externality contexts, such behaviors are often self‐limiting in the context of infectious disease. (2) In market economies, behaviors that may create infectious disease externalities typically occur at sites that are owned privately and visited voluntarily. Owners have powerful incentives to regulate such behaviors at their sites, and visitors face residual infection risk contractually. (3) The social cost of infectious disease externalities is limited by the cheapest method of avoiding externalized infection risk. That cost is modest compared to the one usually imagined: the value of life (or health) lost to the disease if government does not intervene. We elaborate these arguments in the context of the COVID‐19 pandemic.

中文翻译：

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外部性和 COVID-19

在没有政府干预的情况下，传染病的负外部性不那么普遍，而且对社会的成本也比人们通常认为的要低。之所以如此，是因为三个原因。(1) 与许多经典外部性背景下的外部性创造行为不同，这种行为在传染病背景下通常是自限性的。(2) 在市场经济中，可能产生传染病外部性的行为通常发生在私人拥有并自愿访问的场所。业主有强大的动机来规范其站点的此类行为，而访问者则面临合同上的残余感染风险。(3) 传染病外部性的社会成本受到避免外部化感染风险的最便宜方法的限制。与通常想象的相比，这一成本并不高：如果政府不干预，生命（或健康）的价值会因疾病而丧失。我们在 COVID-19 大流行的背景下详细阐述了这些论点。