NEW YORK (NYT NEWS SERVICE).- New York City plans to require visitors and staff members at museums and other cultural institutions to be vaccinated, Mayor Bill de Blasio announced Monday.

“Defeating the delta variant is the best way to support cultural institutions, because it brings us all back,” de Blasio said at a news conference at which he outlined the new requirements. “We believe, if we take these aggressive measures, this is going to encourage a lot of people — audience members and staff alike — to get vaccinated.”

The new vaccine mandate for museums came as the city expanded its “Key to NYC” program, which requires vaccinations in a number of settings, to include “bars, fitness gyms, movie and stage theaters, museums and other indoor venues.” The policy will take effect Tuesday, but enforcement will not begin until Sept. 13 to educate the public and give venues time to adjust.

Children younger than 12, who are not eligible to be vaccinated, will have to be accompanied by a vaccinated person and will be encouraged to wear masks, city officials said.

“We’re saying get at least the first vaccination — of course the goal is to get everyone fully vaccinated — but get at least the first vaccination and you’ll be able to work or enjoy indoor dining, indoor fitness, indoor entertainment, concerts, movie theaters,” the mayor said as he outlined the requirements.

The city plans to conduct a $10 million media campaign to inform the public of the new requirements, according to city officials.

The 33 museums and arts groups operating in city-owned buildings or on city-owned land — known as members of the Cultural Institutions Group — had been in discussions over the past few weeks with the city’s Department of Cultural Affairs.

There was broad consensus among those arts organizations — as well as others that are not city-owned — in favor of a vaccination mandate.

“Everyone wants their audiences and their employees to be safe,” said Lucy Sexton, executive director of New Yorkers for Culture & Arts, an advocacy group.

Proof of vaccination can include a photo or hard copy of an official vaccination card, the state’s Excelsior Pass, New York City vaccination apps or an official vaccine record for authorized vaccines.

This article originally appeared in The New York Times.