美国辛辛那提儿童医院医疗中心Katherine A. Auger团队分析了全州关闭学校和COVID-19发病率和死亡率之间的相关性。2020年7月29日，《美国医学会杂志》发表了这一成果。

美国各州颁布了包括关闭学校在内的非药物干预措施，以减少COVID-19的传播。虽然不确定关闭学校是否有效，但所有50个州仍在2020年3月关闭了学校。

为了确定学校关闭以及关闭时机是否与降低COVID-19的发病率和死亡率相关，2020年3月9日至2020年5月7日，研究组进行了一项基于人口的观察研究，使用中断的时间序列分析，并结合滞后期，以允许潜在政策相关变化发生。主要结局和指标为COVID-19日发病率和每10万居民的死亡率。

在学校关闭时，COVID-19在各州的累积发病率为每10万人0例至14.75例不等。学校关闭后，COVID-19校正后的每周发病率相对降低了62%，死亡率相对降低了58%。学校关闭时累积发病率越低的州，下降幅度越大。例如，COVID-19发病率最低的州，每周发病率降低了72%，而累积发病率最高的州则降低了49%。根据这一分析研究组得出一个模型估计，当COVID-19的累积发病率为最低四分位数时，关闭学校可使26天内每10万人的病例数减少128.7例，16天内每10万人死亡人数减少1.5例。

总之，美国停课政策暂时降低了COVID-19的发病率和死亡率。当COVID-19的累积发病率较低时，较早关闭学校可更大幅度地降低发病率和死亡率。

附：英文原文

Title: Association Between Statewide School Closure and COVID-19 Incidence and Mortality in the US

Author: Katherine A. Auger, Samir S. Shah, Troy Richardson, David Hartley, Matthew Hall, Amanda Warniment, Kristen Timmons, Dianna Bosse, Sarah A. Ferris, Patrick W. Brady, Amanda C. Schondelmeyer, Joanna E. Thomson

Issue&Volume: 2020-07-29

Abstract: Importance  In the US, states enacted nonpharmaceutical interventions, including school closure, to reduce the spread of coronavirus disease 2019 (COVID-19). All 50 states closed schools in March 2020 despite uncertainty if school closure would be effective.

Objective  To determine if school closure and its timing were associated with decreased COVID-19 incidence and mortality.

Design, Setting, and Participants  US population–based observational study conducted between March 9, 2020, and May 7, 2020, using interrupted time series analyses incorporating a lag period to allow for potential policy-associated changes to occur. To isolate the association of school closure with outcomes, state-level nonpharmaceutical interventions and attributes were included in negative binomial regression models. States were examined in quartiles based on state-level COVID-19 cumulative incidence per 100000 residents at the time of school closure. Models were used to derive the estimated absolute differences between schools that closed and schools that remained open as well as the number of cases and deaths if states had closed schools when the cumulative incidence of COVID-19 was in the lowest quartile compared with the highest quartile.

Exposures  Closure of primary and secondary schools.

Main Outcomes and Measures  COVID-19 daily incidence and mortality per 100000 residents.

Results  COVID-19 cumulative incidence in states at the time of school closure ranged from 0 to 14.75 cases per 100000 population. School closure was associated with a significant decline in the incidence of COVID-19 (adjusted relative change per week, 62% [95% CI, 71% to 49%]) and mortality (adjusted relative change per week, 58% [95% CI, 68% to 46%]). Both of these associations were largest in states with low cumulative incidence of COVID-19 at the time of school closure. For example, states with the lowest incidence of COVID-19 had a 72% (95% CI, 79% to 62%) relative change in incidence compared with 49% (95% CI, 62% to 33%) for those states with the highest cumulative incidence. In a model derived from this analysis, it was estimated that closing schools when the cumulative incidence of COVID-19 was in the lowest quartile compared with the highest quartile was associated with 128.7 fewer cases per 100000 population over 26 days and with 1.5 fewer deaths per 100000 population over 16 days.

Conclusions and Relevance  Between March 9, 2020, and May 7, 2020, school closure in the US was temporally associated with decreased COVID-19 incidence and mortality; states that closed schools earlier, when cumulative incidence of COVID-19 was low, had the largest relative reduction in incidence and mortality. However, it remains possible that some of the reduction may have been related to other concurrent nonpharmaceutical interventions.

DOI: 10.1001/jama.2020.14348

Source: https://jamanetwork.com/journals/jama/fullarticle/2769034