Mass gatherings contributed to early COVID-19 mortality: Evidence from US sports

Social distancing is important to slow the community spread of infectious disease, but it creates enormous economic and social cost. Thus, it is important to quantify the benefits of different measures. We study the ban of mass gatherings, an intervention with comparably low cost. We exploit exogenous variation in the number of National Basketball Association and National Hockey League games, which arises due to the leagues' predetermined schedules, and the sudden suspension of the 2019–2020 seasons. We find that, among clusters of counties that are adjacent to sports venues, each additional mass gathering increased the cumulative number of COVID-19 deaths by 10.3%.