School of the Environment, Yale University, New Haven, CT 06511.
Yale Institute for Global Health, New Haven, CT 06510.
Proc Natl Acad Sci U S A. 2021 Apr 20;118(16). doi: 10.1073/pnas.2008814118.
Staying home and avoiding unnecessary contact is an important part of the effort to contain COVID-19 and limit deaths. Every state in the United States enacted policies to encourage distancing and some mandated staying home. Understanding how these policies interact with individuals' voluntary responses to the COVID-19 epidemic is a critical initial step in understanding the role of these nonpharmaceutical interventions in transmission dynamics and assessing policy impacts. We use variation in policy responses along with smart device data that measures the amount of time Americans stayed home to disentangle the extent that observed shifts in staying home behavior are induced by policy. We find evidence that stay-at-home orders and voluntary response to locally reported COVID-19 cases and deaths led to behavioral change. For the median county, which implemented a stay-at-home order with about two cases, we find that the response to stay-at-home orders increased time at home as if the county had experienced 29 additional local cases. However, the relative effect of stay-at-home orders was much greater in select counties. On the one hand, the mandate can be viewed as displacing a voluntary response to this rise in cases. On the other hand, policy accelerated the response, which likely helped reduce spread in the early phase of the pandemic. It is important to be able to attribute the relative role of self-interested behavior or policy mandates to understand the limits and opportunities for relying on voluntary behavior as opposed to imposing stay-at-home orders.
居家并避免不必要的接触是遏制 COVID-19 并减少死亡人数的重要措施。美国每个州都制定了鼓励保持社交距离的政策，有些州甚至强制要求民众居家。了解这些政策如何与个人对 COVID-19 疫情的自愿反应相互作用，是理解这些非药物干预措施在传播动态中的作用以及评估政策影响的关键第一步。我们利用政策反应的差异以及测量美国人居家时间的智能设备数据，来厘清观察到的居家行为变化在多大程度上是由政策引起的。我们有证据表明，居家令以及对当地报告的 COVID-19 病例和死亡人数的自愿反应导致了行为的改变。对于实施居家令的中位数县，该县每出现约两例病例就会实施居家令，我们发现，对居家令的反应使居家时间增加，就好像该县又增加了 29 例本地病例。然而，居家令的相对效果在某些县更为显著。一方面，这一强制措施可以被视为对病例增加的自愿反应的替代。另一方面，政策加速了应对速度，这可能有助于在大流行的早期阶段减少传播。能够将自我利益行为或政策强制的相对作用归因于理解依靠自愿行为而不是实施居家令的限制和机会非常重要。
