Does NFL need to play 2020 in a 'bubble'? Dr. Anthony Fauci says yes.

Much of the energy around return-to-sports conversations is being spent right now on those with the most immediate impending start or resumption dates like the NBA, NHL, MLS, WNBA and — maybe, just maybe, — MLB.

All of those leagues could be playing games or preparing to do so in July, so it makes sense that the focus is on them.

Looming in the distance, though, are two giants: the NFL and college football.

While football has a longer time to sort out its plans on how — or if — a 2020 season can happen, and theoretically benefits from the knowledge of the virus gained during that time, the very nature of the sport itself and the possibility of a second wave of the pandemic this fall are factors that complicate any plans.

So how should football be proceeding? Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN that the sport should be planning to play in a so-called "bubble," with players isolated, much like the NBA and MLS are planning to do in their returns-to-play in Florida.

"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."

Such a measure seems feasible both logistically and economically for the NFL. As ESPN notes, though, that could present a huge challenge for college football — with players spread out on college campuses and, in all likelihood, attending at least some in-person classes.

And perhaps a greater hurdle for both the NFL and college football: containing the spread of the virus, even in a bubble, if a player tests positive — because the very essence of football requires players to be in very close contact with each other play after play.

"That's the perfect setup for spreading (the virus)," Fauci said last month. "I would think that if there is an infected football player on the field — a middle linebacker, a tackle, whoever it is it — as soon as they hit the next guy, the chances are that they will be shedding virus all over that person."

Earlier this week, it was revealed that several players from both the NFL's Houston Texans and Dallas Cowboys — including star running back Ezekiel Elliott — tested positive for the virus, though none of the players from either team were reportedly at team facilities.

I've tended to assume football — and the NFL in particular — will figure out a way to play a full season.

But while football could benefit from learning from the successes and mistakes of other leagues over the next couple months, the summer months could also provide more questions than answers about the logistics and feasibility of that assumption.