Dr. Anthony Fauci is cautiously optimistic about the prospect of fans returning to the stands for the 2021 MLB season, telling ESPN's Buster Olney there's a "pretty good chance" of it happening if the rate of COVID-19 infections continues to drop.

"We could have a pretty good chance of having a baseball season that's a full season," Fauci, the nation's top infectious disease expert, said on ESPN's Baseball Tonight Podcast. "That we could have people in the stands, maybe not right next to each other; there are going to be public health restrictions like mask wearing and things like that."

Fauci cautioned that fan attendance would be dependent on current trends holding and that the full impact of certain coronavirus variants remains to be seen.

Spring training is expected to start with limited fans throughout Florida and Arizona, pending local approval, with teams such as the Boston Red Sox, Houston Astros and Washington Nationals having tickets on sale now.

Fan attendance for the season is determined by local municipalities, but clubs are required to submit a plan to the league office that must be approved as consistent with the advice of their health experts. The Tampa Bay Rays are one team that has announced a specific plan -- in their case, 7,000 fans allowed at Tropicana Field -- for the start of the season in April.

Fauci is uncertain when MLB will see the return of full stadiums, saying it would likely take 75-80% of the population being vaccinated with the rate of infection staying very low.

ESPN's Jesse Rogers contributed to this report.