Background: Shutdowns are enacted when alternative public health measures are insufficient to control the epidemic and the population is largely susceptible. An age-stratified agent-based model was developed to explore the impact of shutdowns to control SARS-CoV-2 transmission in Canada under the assumption that current efforts to control the epidemic remains insufficient and in the absence of a vaccine. Methods: We estimated the current levels of interventions in Canada to generate a baseline scenario from 7 February to 7 September 2020. Four aspects of shutdowns were explored in scenarios that ran from 8 September 2020 to 7 January 2022, these included the impact of how quickly shutdowns are implemented, the duration of shutdowns, the minimum break (delays) between shutdowns and the types of sectors to shutdown. Comparisons among scenarios were made using cases, hospitalizations, deaths and shutdown days during the 700-day model runs. Results: We found a negative relationship between reducing SARS-CoV-2 transmission and the number of shutdown days. However, we also found that for shutdowns to be optimally effective, they need to be implemented fast with minimal delay, initiated when community transmission is low, sustained for an adequate period and be stringent and target multiple sectors, particularly those driving transmission. By applying shutdowns in this manner, the total number of shutdown days could be reduced compared to delaying the shutdowns until further into the epidemic when transmission is higher and/or implementing short insufficient shutdowns that would require frequent re-implementation. This paper contrasts a range of shutdown strategies and trade-offs between health outcomes and economic metrics that need to be considered within the local context. Interpretation: Given the immense socioeconomic impact of shutdowns, they should be avoided where possible and used only when other public health measures are insufficient to control the epidemic. If used, the time it buys to delay the epidemic should be used to enhance other equally effective, but less disruptive, public health measures.

背景：当替代性的公共卫生措施不足以控制该流行病并且该人群在很大程度上易受感染时，将实施停工。建立了一个基于年龄分层的基于代理的模型，以研究停药对控制SARS-CoV-2传播在加拿大的影响，其前提是当前控制流行病的努力仍然不足且没有疫苗。方法：我们估计了加拿大目前为产生2020年2月7日至2020年9月7日的基准情景而进行的干预的水平。从2020年9月8日至2022年1月7日的情景中，探讨了停工的四个方面，其中包括快速实施的影响。执行关机，关机持续时间，关机之间的最小间隔（延迟）以及要关机的扇区类型。在700天的模型运行期间，使用病例，住院，死亡和停工天数对方案进​​行了比较。结果：我们发现减少SARS-CoV-2传播与关闭天数之间存在负相关关系。但是，我们还发现，要使关机达到最佳效果，就必须以最小的延迟快速实施关机；当社区传播率低，持续时间足够长，严厉并针对多个部门（尤其是推动传播的部门）时，便应开始实施。通过以这种方式应用关闭，与将关闭延迟到当传输更高时进一步流行到流行病和/或实施短暂不足的关闭（需要频繁重新实施）相比，可以减少关闭天的总数。本文对比了在当地情况下需要考虑的一系列关闭策略和健康结果与经济指标之间的权衡。解释：鉴于停药对社会经济的巨大影响，应在可能的情况下避免停药，只有在其他公共卫生措施不足以控制该流行时才应使用停药。如果使用了它，花了一些时间来延迟流行，应该用来增强其他同样有效但破坏性较小的公共卫生措施。