New York City will impose a vaccine mandate on all private employers in an attempt to thwart the omicron variant.

The policy – the first of its kind in the nation – was announced by Mayor Bill de Blasio on Monday and will take effect December 27th. It impacts approximately 184,000 businesses. CBS News New York reports that there will be a weekly testing option.

In addition, starting on December 14th, vaccine requirements to enter restaurants, gyms, and entertainment venues will be stepped up and expanded. Children ages 5-11 will now have to show proof of one shot while people 12 and older will now have to show that they’ve received two doses (or a single Johnson and Johnson jab).

Children will also need to be vaccinated to participate in high-risk extracurricular activities like band, sports, and dance.

“Omicron is here, and it looks like it’s very transmissible,” de Blasio said on MSNBC. “The timing is horrible with the winter months.”

“We in New York City have decided to use a preemptive strike, to really do something bold to stop the further growth of COVID and the dangers it’s causing to all of us,” he added.

He said the city is confident it will withstand legal scrutiny because its universal.

The city already requires all city workers to be vaccinated.

CNBC provides key context:

New York has identified eight cases of the omicron variant as of the weekend, seven in the New York City area and one in Suffolk County on Long Island.

Covid cases are increasing in New York City, with more than 1,500 new cases confirmed daily on average, according to the city health department