Dr. Anthony Fauci says football teams would need to emulate plans by the NBA and MLS for a "bubble" format or consider not playing in 2020 because of the coronavirus pandemic.

Fauci is the director of the National Institute of Allergy and Infectious Diseases and a key member of the White House task force on the virus. He told CNN that football players would need to be isolated from others and tested regularly.

"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 said. "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."

While the NFL could follow its pro basketball and soccer counterparts and consider isolating players to begin the season, it is unclear how college teams could do the same on university campuses.

The NFL has maintained that it will start its regular season as scheduled on Sept. 10, when the Kansas City Chiefs host the Houston Texans. The offseason program has been conducted remotely, but the plan is for training camps to be held in person starting in late July.

NFL chief medical officer Dr. Allen Sills noted Fauci's comments in a statement, saying the league, the players' union and joint medical advisers are addressing issues to mitigate health risks.

"We are developing a comprehensive and rapid-result testing program and rigorous protocols that call for a shared responsibility from everyone inside our football ecosystem," Sills said. "This is based on the collective guidance of public health officials, including the White House task force, the CDC, infectious disease experts, and other sports leagues.

"Make no mistake, this is no easy task. 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. We will be flexible and adaptable in this environment to adjust to the virus as needed."

A source told ESPN's Jeremy Fowler earlier this week that the NFL Players Association told its members that they could be tested roughly every three days for COVID-19 and isolated if they test positive.

On Wednesday, the NCAA Division I Council approved a six-week practice plan for football that begins in July in hopes of starting the 2020 season on time.

In May, Fauci said football is the "perfect setup" to spread the coronavirus, noting the close contact that players engage in every play.