The N.F.L. and the N.F.L. Players Association agreed to suspend all Covid-19 protocols, effective immediately, returning teams and players to pre-pandemic operations for the first time since March 2020. The N.F.L., which is not in season, is the first of the United States’ major professional sports leagues to halt its coronavirus-related policies.

Players and team staff members will no longer be required to wear masks inside facilities, adhere to social distancing measures or restrict access within team buildings based on vaccination or job function, according to a memo sent to all 32 teams on Wednesday, though each team will have to comply with local ordinances governing mask mandates.

Teams are expected to provide an area where P.C.R. tests can be run on-site for anyone who self-reports coronavirus symptoms, but there will be no mandatory testing cadence. Those who test positive will be required to isolate for five days, as per current recommendations from the Centers for Disease Control and Prevention.

The memo cited “encouraging trends” regarding the prevalence and severity of Covid-19 cases, evolving guidance from the C.D.C. and changes to state laws as reasons for the change.

New case numbers and hospitalizations have fallen sharply from the nationwide peak in January. The N.F.L. said in the memo that it would work with the players’ union and medical experts to monitor whether protocols needed to be reimposed in full or in part.

Zachary Binney, a sports epidemiologist at Oxford College of Emory University in Georgia, said the league’s decision was largely in accordance with revised C.D.C. guidelines, though he added that the federal agency’s guidelines still supported indoor mask usage in high-risk areas.

The N.F.L. had a surge of cases during the rise of the Omicron variant in the United States, with more than 1,200 positive tests recorded among players and staff from Dec. 12 to Jan. 8. But the league did not report any positive tests between the divisional round playoff games and the Super Bowl. In the final weeks of the 2021 season, the league dropped testing of asymptomatic players, regardless of vaccination status.

Nearly 95 percent of players and close to 100 percent of team personnel were vaccinated, according to the N.F.L. The league mandated in December that all team staff members who were in close contact with players receive a booster shot. Last month, the league said only about 10 percent of players had been boosted, but that number may have gone up since the end of the season.