Starting this Saturday, all NFL teams must operate under the league's intensive COVID-19 protocols for the remainder of this season, according to a league memo sent to teams Wednesday afternoon and obtained by ESPN.

Requirements under the intensive protocols, which 28 of the league's 32 teams have already experienced at some point this season, include virtual team meetings and the wearing of masks by all players and staff at all times while at the facility, including during practice.

"It has been said many times that our 2020 season cannot be 'normal' because nothing about this year is normal," NFL commissioner Roger Goodell wrote in the memo. "Flexibility and adaptability have been critical to our success to date and we must continue with that approach."

The league said it made the decision to impose the intensive protocols league-wide because of the heightened recent spread of COVID-19 around the country as well as the data it has been collecting all year regarding close contacts.

All players and staff this year are required to wear contact tracing devices while in the facility and while traveling, so that the league and union can quickly identify close contacts of an individual who tests positive. The league says that since Week 5, teams that have been in the intensive protocols have seen a greater than 50% reduction in close contacts, which both reduces the chances for spread and makes contact tracing easier and more efficient.

To this point, teams have been instructed to enter the intensive protocols when someone in their building has tested positive or when they have recently played against a team that had someone test positive. The league's memo says 28 teams have already been in the intensive protocols at least once this year and 16 have been in them at least twice.

Details of the intensive protocols include:

• A requirement that all meetings be held virtually or in the largest possible indoor space, provided such space has been inspected and approved by the NFL and the NFLPA.

• Grab-and-go meal service in team cafeterias.

• Limited time spent in locker rooms -- less than 15 minutes per person per session, with sessions scheduled so as to minimize the number of people in the locker room at one time.

• Masks or league-approved Oakley helmet face shields at all times in every part of the facility, including on the practice field.

• "Double PPE" during medical treatment for both the patient and the provider -- i.e., a player receiving treatment for an injury must wear both a mask and a face shield during that treatment and so must the doctor or trainer performing the treatment.

• A limit of 10 players and five coaches at any one time in the weight room, regardless of the size of the room.

"As we continue through the season, it will likely be necessary to take further steps to address broader conditions," the memo says. "In conjunction with our medical advisors and the NFLPA, we will continue to incorporate our experience and implement enhancements to the protocols and communicate with each of you on a regular basis."