University settings have demonstrated potential for coronavirus disease (COVID-19) outbreaks; they combine congregate living, substantial social activity, and a young population predisposed to mild illness. Using genomic and epidemiologic data, we describe a COVID-19 outbreak at the University of Wisconsin–Madison, Madison, Wisconsin, USA. During August–October 2020, a total of 3,485 students, including 856/6,162 students living in dormitories, tested positive. Case counts began rising during move-in week, August 25–31, 2020, then rose rapidly during September 1–11, 2020. The university initiated multiple prevention efforts, including quarantining 2 dormitories; a subsequent decline in cases was observed. Genomic surveillance of cases from Dane County, in which the university is located, did not find evidence of transmission from a large cluster of cases in the 2 quarantined dorms during the outbreak. Coordinated implementation of prevention measures can reduce COVID-19 spread in university settings and may limit spillover to the surrounding community.

大学环境已显示出冠状病毒病 (COVID-19) 爆发的可能性；它们结合了集体生活、大量的社会活动以及容易患轻度疾病的年轻人口。我们利用基因组和流行病学数据，描述了美国威斯康星州麦迪逊市威斯康星大学麦迪逊分校爆发的 COVID-19 疫情。 2020年8月至10月期间，共有3,485名学生检测呈阳性，其中宿舍学生为856/6,162人。病例数在2020年8月25日至31日入住周期间开始上升，然后在2020年9月1日至11日期间迅速上升。学校启动了多项预防措施，包括隔离2个宿舍；随后观察到病例数有所下降。对大学所在戴恩县的病例进行基因组监测，没有发现疫情爆发期间两个隔离宿舍中出现大群病例传播的证据。协调实施预防措施可以减少 COVID-19 在大学环境中的传播，并可能限制病毒向周边社区的蔓延。