National Football League (NFL) games attended by fans during the 2020-21 season were linked with increased COVID-19 case rates in the counties where they were held, and in those surrounding the stadiums.
Results of a new study, published in JAMA Network Open, show the spikes were more prominent when games had over 20,000 attendees, while those with under 5,000 fans were not associated with higher case rates.
The findings suggest “large events should be handled with extreme caution during public health event(s) where vaccines, on-site testing, and various countermeasures are not readily available to the public,” authors wrote.
In March 2020, the NFL made the controversial decision to hold its 2020-21 professional season in the wake of the COVID-19 pandemic.
As part of their decision, teams underwent continuous testing and contact tracing, and through these measures the league was able to maintain relatively low rates of infection among players and staff, JAMA authors explained. However, less is known about how the season affected fans who attended the games.
A total of 269 home games were included in the analysis. Researchers measured COVID-19 case rates seven, 14, and 21 days after each game, and compared rates of games with and without in-person attendance.
Over 1 million fans attended all the games. Games with over 20,000 fans were associated with 2.23 times higher COVID-19 infection rate spikes than those with lower attendance.
“We found very little evidence of spikes in the first 7-day postgame window, regardless of spatial resolution (eg, in-county, surrounding counties, all counties), which was somewhat expected given the incubation period of the virus variant,” authors wrote. However, 14 and 21 days after in-person games, both the counties where the games took place and surrounding counties saw spikes in COVID-19 cases.
Fans were permitted to attend 117 games where crowds ranged in size from 748 to 31,700. Of the 32 teams in the league, 20 allowed fans to attend some or all of the home games, although COVID-19 mitigation strategies differed by stadium. Both the Dallas Cowboys and the Tampa Bay Buccaneers allowed over 20,000 fans at a time to attend their games.
Areas with less stringent COVID-19 restrictions may have been more encouraging of fan attendance, authors noted, and the study was not able to determine whether the increase in case rates was due to fan attendance at the stadium, tailgating around the stadium, or family and friends congregating in homes after games.
“Public health decision-makers still lack concrete evidence for attributing a spike in any cases to one part of the overall football fan experience,” wrote Stephanie S. Johnson and Eric T. Lofgren of Washington State University in an accompanying editorial.
The study was carried out before the emergence of the Delta and Omicron variants.
