The NFL implemented a new set of COVID-19 protocols Monday in response to one team outbreak and a series of other positive tests that forced multiple changes to the Week 4 game schedule.

In a memo released after a call with officials of every team, commissioner Roger Goodell called on clubs to "recommit ourselves to our protocols and best practices for the duration of the season."

Moving forward, Goodell wrote, the league will issue discipline that could include loss of draft choices or forfeit of a game if protocol violations occur that result in the spread of the virus, adjustments to schedule or other unspecified league impact.

"The protocols do not implement themselves," Goodell added, "and our progress thus far cannot lead us to complacency. Complacency is our shared opponent."

According to the memo, the league will now:

* Require a longer onboarding process for free-agent tryouts

* Limitations on the number of tryouts per week

* Ban on gatherings outside the club facility

* Implement a video monitoring system to ensure compliance with protocols.

In addition to the new requirements, the NFL has recommended taking all meetings virtual and wearing masks or shields during practices and walk-throughs. It also has suggested a decrease in the size of the traveling party and a reduction of the amount of time spent in lunch rooms and locker rooms.

A total of 20 Tennessee Titans players and other staff members have returned positive tests since Sept. 24. The NFL and NFLPA haven't revealed results of its ongoing investigation, and it's not known whether the Titans violated any preexisting protocols. But the NFL's decision to lengthen the intake process is notable because the Titans' first known positive test was practice squad defensive back Greg Mabin. His positive results became known three days after he was signed.

The Titans' Week 4 game against the Pittsburgh Steelers was postponed until later this season. The New England Patriots and Kansas City Chiefs, meanwhile, had their game pushed back from Sunday to Monday night because of one positive test for each team.

The new ban on gatherings outside the team facility, meanwhile, was a nod toward a charity event that multiple Las Vegas Raiders players attended last week. Among other things, the players -- including quarterback Derek Carr -- were seen in pictures not wearing masks. Earlier this season, the NFL fined five coaches $100,000 apiece, and their teams $250,000 each, for not properly wearing face coverings on the sidelines during games. Those coaches were: Vic Fangio (Denver Broncos), Pete Carroll (Seattle Seahawks), Kyle Shanahan (San Francisco 49ers), Jon Gruden (Raiders) and Sean Payton (New Orleans Saints).