Economists Alexander Ahammer, Martin Halla and Mario Lackner (Institute of Economics) studied 78 National Basketball Association (NBA) matches and 57 National Hockey League (NHL) matches played at the beginning of March 2020. The leagues only stopped playing on March 12. Too late, as it turns out, as the impact of the well-attended sporting events are measurable: per game, the number of infected individuals increased by 380 per million residents, meaning a 13% increase in the Covid cases. There were also an additional 16 deaths (an increase of 11%).

The reason is fairly obvious as Ahammer explained: "On average, approximately 18,000 people attended these kinds of sporting events." These events were also held indoors, helping to create a super-spreading environment. And because game schedules are not politically dependent, sporting event organizers were not subject to any kind of political decisions. The study conducted in 242 counties did not show a difference between regions that implemented and adhered to Covid measures as opposed to those that had less strict measures.

The study titled "Mass Gatherings Contributed to Early COVID-19 Spread: Evidence from US Sports" is currently being submitted to a renowned journal for publication and should serve as a warning: The US leagues plan to resume games on July 30.