According to amended instructions issued on Friday, masks are no longer necessary at the three major movie theatre chains in the United States for persons who have been completely vaccinated against the coronavirus.

On their websites, AMC Entertainment, Cinemark, and Regal Cinemas stated that moviegoers who have not been completely vaccinated would be urged to continue wearing masks and that additional social-distancing precautions and cleaning processes would remain in place.

“In compliance with CDC standards, masks are not necessary for fully vaccinated guests,” AMC stated on its website, referring to the Centers for Disease Control and Prevention in the United States. “If you have not been properly vaccinated, we ask that you wear a mask during the performance unless you are actively enjoying food or drinks.”

Similar changes to the mask policy have been implemented on the Regal and Cinemark websites. All three chains stated that they will adhere to state and municipal requirements for mask use, which may differ from the CDC standards.

The adjustments for movie theatres come just two weeks after the CDC said that fully vaccinated persons do not need to wear masks in any venue.

Following extended pandemic-related closures and a paucity of fresh film releases, moviegoing in the United States has begun to pick up.

Last week, movie studios and theatre chains started a “big screen is back” promotion, teasing a summer packed with blockbusters such as the new “Fast & Furious” feature and the superhero feature “Black Widow.”

Hollywood studios are keeping a tight eye on the box office profits for two blockbuster films that will be released this weekend: “Cruella,” a prequel narrative about the villain from “101 Dalmatians,” and the thriller “A Quiet Place Part II.”