Editor’s note: Find the latest COVID-19 news and guidance in Medscape’s Coronavirus Resource Center.
During its pandemic season, the National Football League found that people can transmit the coronavirus in fewer than 15 minutes of interaction with others, according to a new report published Monday by the CDC.
Four major factors played into COVID-19 transmission: whether masks were worn, how well the room was ventilated, how long the interaction lasted and the distance between the people.
“The most impactful interventions were universal use of face masks, holding meetings outside and minimizing in-person meetings, closing dining rooms — those all have broad applicability outside of football,” Allen Sills, MD, the NFL chief medical officer, told NFL.com.
The NFL and CDC teamed up to look at lessons learned through the year. Overall, they said, the COVID-19 protocols and contact tracing efforts implemented in July allowed 32 teams to complete the season and compete in playoffs, with the Super Bowl still to come.
Throughout the season, players and other team personnel wore devices that tracked how long they interacted with others when they were within six feet of another person. The research team found that strict protocols after a potential COVID-19 exposure, such as quarantining high-risk contacts and having stringent mask requirements, were the most helpful ways to prevent the spread of the virus.
From August through November, about 11,400 players and staff took 623,000 COVID-19 tests, and 329 were positive. Between Sept. 27 through Oct. 10, 41 cases were identified, including 21 connected to transmission among one team, forcing the team to close its facilities.
Contact tracing found that multiple instances of transmission likely occurred in less than 15 minutes of interaction within six feet of space. Among the 21 players who were connected, 12 had no interactions that lasted more than 15 minutes, including 8 who had no interactions that lasted longer than 5 minutes.
“Interviews revealed that, among the brief interactions that did occur, some were during unmasked meetings in small rooms or while eating,” according to the report.
After the cluster of cases, several league-wide changes were implemented, including intensive protocols whenever a positive test came back, such as daily testing and 5-day quarantines of high-risk contacts. If any players or staff members tested positive, the entire club would follow the strict protocols.
Between Oct. 1 and Nov. 21, the number of interactions that lasted for 15 minutes or longer dropped by 60%, and 189 players and staff members were quarantined after a potential exposure. Among those, 20 people from 12 teams tested positive, and most cases came from household members or outside contacts. No secondary cases within the team were identified.
The cases often stemmed from unmasked indoor activities, sharing a ride while unmasked and eating and drinking in close proximity, according to the report.
Strict protocols — such as quarantining people who may have been exposed — could help in schools, long-term care facilities and high-density environments, the research team wrote. Intensive protocols should be tailored to each environment and include extensive masking, outdoor venues and restricted meal-time interactions, they added.
“We were able to show that you can play a team sport while minimizing risk to the participants,” Sills told The Associated Press. “It does require everyone to do their part every day. It also requires some modifications of certain activities.”
CDC, “Morbidity and Mortality Weekly Report, Implementation and Evolution of Mitigation Measures, Testing, and Contact Tracing in the National Football League, August 9–November 21, 2020.”
NFL.com, “CDC, NFL hope findings of what makes a close contact high risk will limit public spread of COVID-19.”
Associated Press, “CDC publishes paper on NFL’s efforts”