NFL players should avoid engaging in group workouts as COVID-19 cases are rising again in the United States, the medical director of the sport's players association said on Saturday.
Major League Soccer, the National Football League, the National Hockey League and Major League Baseball all confirmed positive tests in a single 24-hours period Friday.
"It is our consensus medical opinion that in light of the increase in COVID-19 cases in certain states that no players should be engaged in practicing together in private workouts," NFLPA Medical Director Thom Mayer said in a statement.
"It is in the best interest of all players that we advise against any voluntary joint practices before training camp commences."
The NFL did not immediately respond to a request for comment.
The COVID-19 outbreak has claimed more than 121,000 lives in the United States, and there has been a surge in new cases in several states this week.
Teams from the MLB and the NHL, including the Philadelphia Phillies and Tampa Bay Lightning, closed Florida facilities on Friday after some players tested positive, casting doubt on the return of professional sports in North America.
The NFL said on Thursday that it would "make adjustments as necessary" to keep players safe after top U.S. health official Anthony Fauci cast doubt on the 2020 season, which is set to kick off in September.