The NFL has been quiet on how it will approach the 2020 season, but there is growing concern that it will be as limited as other sports.

Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, believes the NFL will need a bubble to play in 2020.

“Unless players are essentially in a bubble —insulated from the community and they are tested nearly every day — it would be very hard to see how football is able to be played this fall,” Fauci told CNN’s Sanjay Gupta. “If there is a second wave, which is certainly a possibility and which would be complicated by the predictable flu season, football may not happen this year.”

The NBA, WNBA, and tennis have made plans to incorporate bubbles into seasons. The common denominators are regular testing, temperature checks, designated hotels, and all games’ being played at a central location.

If the NFL takes this route, it will likely face a harder task than any other sport. Each finalized NFL roster has 53 players, plus 12 practice squad players. Supplying lodging for 65 players per team would mean finding hotels for more than 2,000 players, coaches, and personnel league-wide.

It would be the largest gathering of people in a bubble for any sport. Not to mention, hosting 14 or more games each week will probably mean more Saturday or Monday contests if the games are limited to three or four stadiums.

Plenty of factors have to be considered with pro football. With college football, it’s even more difficult because players are on college campuses.

NFL chief medical officer Allen Sills responded to Fauci’s comments.

“Make no mistake, this is no easy task,” Sills said in a statement. “We will make adjustments as necessary to meet the public health environment as we prepare to play the 2020 season as scheduled with increased protocols and safety measures for all players, personnel, and attendees.”

Fauci said in May that football is the “perfect setup” for the coronavirus to continue to spread. The NFL will have to closely monitor the successes and failures of other leagues while also being creative with its own guidelines because of its large numbers of personnel.