Schools around the world are again the site of a large, and largely uncontrolled, experiment. When schools reopened in April and May as the first wave of COVID-19 cases subsided, the virus stayed mostly at bay. Health and education officials cheered, relieved that the huge benefits of in-person schooling seemed to outweigh the risk of viral spread among children and teachers—and from schools to wider communities. As a result, many places that had moved cautiously at first threw open classroom doors in August and September. But the backdrop is very different now: In many areas, COVID-19 has surged to even higher levels than early in the year. In July, Science examined the mostly encouraging lessons from the first reopenings. Now, scrutiny of school openings in countries where the virus is resurgent paints a more complex picture of the risks and how they might be managed. 

世界各地的学校再次成为大型且很大程度上不受控制的实验场所。当第一波COVID-19病例消退时，学校在4月和5月重新开放时，该病毒主要停留在海湾。卫生和教育官员欢呼雀跃，松了一口气，因为面对面的学校教育所带来的巨大好处似乎超过了在儿童和教师之间以及从学校到更广泛的社区传播病毒的风险。结果，许多刚开始谨慎移动的地方在8月和9月就打开了教室的门。但是现在的情况已经大不相同了：在许多地区，COVID-19的水平甚至比年初还要高。7月， 科学 研究了从第一次重新开放以来最令人鼓舞的教训。现在，在病毒重新流行的国家/地区对学校开学情况进行审查，可以更全面地了解这些风险及其应对方法。