NFL players and the working staff of teams will not have to wear masks at team facilities as long as they are fully vaccinated against COVID-19, announced the league's health and safety department.

That decision was made following the update by the Centers for Disease Control and Prevention on the COVID-19 mask policy in the U.S. on Thursday. The definition of "fully vaccinated" is that 14 days passed since one takes the second shot of the Pfizer and Moderna vaccines or the single shot from Johnson & Johnson.

The NFL expects additional modifications to come that will reflect "the greatly reduced risk of viral infection and transmission in fully vaccinated individuals."

"It felt pretty good," said Kevin Stefanski, head coach of the Cleveland Browns, after learning the change of policy on the practice field during rookie camp Friday. "There were some people I didn't realize what they looked like."

The league worked hard last season to make people comply with COVID-19 protocols. For example, coaches were fined for not wearing masks on the sidelines during games; the NFL even threatened to seize teams' draft picks if coaches take off their masks on the sidelines; neither were they allowed to approach referees without wearing a mask.

Having watched multiple games postponed because of the coronavirus last season and the surge of infections in several team bases, the NFL is trying to learn from these lessons. It's not requiring but encouraging players to get vaccinated. Non-player team staff can reject vaccination for medical or religious reasons, but they can't interact with players before getting vaccinated.

The 2021 NFL regular season will kick off on September 9 between the Tampa Bay Buccaneers and the Dallas Cowboys at Raymond James Stadium in Tampa, Florida.