National Football League (NFL) Commissioner Roger Goodell has said the new coronavirus still poses challenges to the league as it prepares to open training camps for all players on Tuesday.
With pre-season games canceled and fan attendance limited in many stadiums across the United States, "the NFL in 2020 will not look like other years," he wrote in an open letter to fans.
"Everyone in the team environment must follow rigorous health and safety protocols to keep themselves and each other safe," added Goodell. "When there is a positive test, strict regulations will be enforced to isolate and care for that individual and to contain the virus before it spreads."
The letter comes as a number of players on Major League Baseball's (MLB) Miami Marlins team tested positive for COVID-19 just four days after MLB started its shortened, coronavirus-delayed season, a potentially ominous development for other major professional sports leagues in North America.
The NFL said it has worked with medical experts, public health officials and state and local governments to develop its return-to-play plan, with the league and players agreeing to changes to the 2020 collective bargaining agreement on Friday.
Players and coaches must submit to regular testing, "including every day for a while," said Goodell, and the league has previously stated that any fans attending games must wear face coverings.
"In the months since the COVID-19 pandemic turned the world upside down, we have navigated the time carefully, thoughtfully and in partnership with the NFL Players Association with a shared goal of playing a healthy and complete 2020 season," he added.
"COVID-19 will continue to present a major challenge to nearly every area of American life. Football is no exception."