Training camp for the NFL's 2020 season is due to start next month, and the season is scheduled to kick off Sept. 10 -- but one of the nation's top infectious disease doctors is issuing the league a warning.

Dr. Anthony Fauci says the NFL's plan to prevent COVID-19 infections must include plans to isolate players and personnel, or they shouldn't have a season.

Fauci says "football may not happen this year" if a second wave of the virus occurs.

The NFL is working on prevention plans, but hasn't spoken about quarantining plans. On Thursday, the league's chief medical officer responded to Fauci's concerns, saying the league is working on a comprehensive COVID-19 testing program.

He added that the plan is no easy task, and will feature adjustments as necessary to meet the public health environment that the country is in when the season begins.