BOSTON (CBS) — The NBA plans on getting back into action with a “bubble” environment in Walt Disney World this summer. Dr. Anthony Fauci, the country’s foremost expert on infectious diseases, believes the NFL may have to follow a similar model if the league hopes to have a season in 2020.

Speaking to CNN this week, Fauci said that an NFL plan that involves teams based in their home cities around the country may prove to be too difficult.

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“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 Dr. Sanjay Gupta of CNN.

Without that scenario, Fauci warned a football season may not be possible in the so-called “second wave” of the coronavirus pandemic.

“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,” Fauci said.

While some states have made tremendous progress in lowering the coronavirus numbers, other states — like Arizona, Texas, and Florida — have seen cases rise in recent weeks.

The NFL has not been immune from the spikes. Ezekiel Elliott is reportedly one of four Texas-based NFL players to test positive for COVID-19, while Broncos defensive back Kareem Jackson also tested positive, as did fellow Bronco Von Miller.

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While Fauci didn’t explore the specific aspects that make football difficult to function during a pandemic, one can’t help but wonder how teams with 90 players plus dozens of coaches, trainers and staff can operate safely and smoothly. And considering NFL teams have 350 percent larger rosters than NBA teams, plus more coaches and staff, there may not even be a location that could work as a suitable “bubble” even if the NFL did not want to pursue such an option. The element of timing also doesn’t work in the NFL’s favor, as training camps are scheduled to open at the end of July. Plus, the regular heavy contact involved in every football drill and snap cannot help the efforts to limit the potential spread of a virus.

Fauci’s warnings also extended to baseball, as he suggested that MLB should not hold the World Series in its usual spot on the calendar.

“I would try to keep [the season] in the core summer months and end it not with the way we play the World Series, until the end of October when it’s cold,” Fauci told The Los Angeles Times. “I would avoid that.”

Fauci’s specific warnings for baseball would logically apply to football, as well.

“This virus is one that keeps fooling us. Under most circumstances — but we don’t know for sure here — viruses do better when the weather starts to get colder and people start spending more time inside, as opposed to outside. The community has a greater chance of getting infected,” Fauci explained. “The likelihood is that, if you stick to the core summer months, you are better off, even though there is no guarantee. … If you look at the kinds of things that could happen, there’s no guarantee of anything. You would want to do it at a time when there isn’t the overlap between influenza and the possibility of a fall second wave.”

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From the very start of the pandemic, the NFL has moved forward as normally as possible, with free agency and the draft taking place mostly without a hitch. Since then, OTAs and minicamps were canceled as teams slowly begin to reopen facilities in phases. While the outlook has always remained optimistic, Dr. Fauci’s warning should provide a reminder that no plans can be guaranteed at this point in time, given the unpredictable nature of the virus.