Do sporting events amplify airborne virus transmission? Causal evidence from US professional team sports

We analyze the impact of professional sporting events on local seasonal influenza mortality to develop evidence on the role played by spectator attendance at sporting events in airborne virus transmission. Results from a difference-in-differences model applied to data from a sample of US cities that gained new professional sports teams over the period 1962–2016 show that the presence of games in these cities increased local influenza mortality by between 4% and 24%, depending on the sport, relative to cities with no professional sports teams and relative to mortality in those cities before a new team arrived. Influenza mortality fell in cities with teams in some years when work stoppages occurred in sports leagues. Health policy decisions, and decisions about the subsidization of professional sports, should take into account the role played by sporting events in increasing airborne virus transmission and local influenza and coronavirus mortality.