Some infectious diseases, such as COVID-19 or the influenza pandemic of 1918, are so harmful that they justify broad-scale social distancing. Targeted quarantine can reduce the amount of indiscriminate social distancing needed to control transmission. Finding the optimal balance between targeted versus broad-scale policies can be operationalized by minimizing the total amount of social isolation needed to achieve a target reproductive number. Optimality is achieved by quarantining on the basis of a risk threshold that depends strongly on current disease prevalence, suggesting that very different disease control policies should be used at different times or places. Aggressive quarantine is warranted given low disease prevalence, while populations with a higher base rate of infection should rely more on social distancing by all. The total value of a quarantine policy rises as case counts fall, is relatively insensitive to vaccination unless the vaccinated are exempt from distancing policies, and is substantially increased by the availability of modestly more information about individual risk of infectiousness.

一些传染病，例如新冠肺炎 (COVID-19) 或 1918 年流感大流行，危害性非常大，因此需要大规模的社会隔离。有针对性的隔离可以减少控制传播所需的不加区别的社会距离。通过最大限度地减少实现目标再生数所需的社会隔离总量，可以在有针对性的政策与大规模政策之间找到最佳平衡。最优性是通过基于风险阈值的隔离来实现的，该风险阈值在很大程度上取决于当前疾病的流行情况，这表明应在不同的时间或地点采用截然不同的疾病控制政策。鉴于疾病流行率较低，有必要采取积极的隔离措施，而基础感染率较高的人群则应更多地依赖所有人的社交距离。隔离政策的总价值随着病例数的下降而上升，对疫苗接种相对不敏感，除非接种疫苗的人不受疏远政策的约束，并且由于提供了更多关于个人传染风险的信息而大大增加了隔离政策的总价值。