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New York City mayor Bill de Blasio announced new vaccine mandates covering all private-sector workers and children ages 5-11.

De Blasio announced on Monday that the new mandate, effective Dec. 27, is a “preemptive strike” to stop the new Covid-19 omicron variant, which causes mild to no symptoms.

“We’ve got omicron as a new factor, we’ve got the colder weather, which is going to really create additional challenges with the delta variant, we’ve got holiday gatherings,” de Blasio said during an appearance on MSNBC’s Morning Joe.

“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 danger it’s causing to all of us.

“So as of today we’re going to announce a first in the nation measure, our health commissioner will announce a vaccine mandate for private-sector employers across the board, all private sector employers in New York City will be covered by this vaccine mandate as of Dec. 27.”

De Blasio also announced that starting Dec. 14 children ages 5-11 will have to show proof of vaccination to attend indoor entertainment or activities.

NYC residents ages 12 and older already are required to show proof of vaccination in order to enter restaurants or fitness facilities.

NYC’s Covid mandates are the strictest of any major metropolitan city in the US.

De Blasio’s term as mayor ends at midnight on January 1, 2022 when Mayor-elect Eric Adams begins his term.