Children ages 5 and up now need to show proof they've received at least one dose of vaccine to enter most businesses -- including theaters, gyms and restaurants -- in the city.
The mandate also includes some extracurricular activities.
The rule expands again on December 27, when anyone over the age of 12 will be required to show proof of a full two-dose vaccination.
NYC vaccine mandate expands, Hochul defends mask rules
"We want to protect everyone," Mayor Bill de Blasio said. "We want to protect our youngest New Yorkers. We know omicron had a lot of impact on younger folks. We know we need a whole family to be safe, and if the youngest kids are safe that also helps protect our seniors."
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Meanwhile, Hochul cited a holiday surge of COVID happening now to defend the most recent order -- which took effect Monday -- that all indoor public places without a vaccine mandate require masks.
The number of cases is up statewide over 58% since Thanksgiving, and the number of hospitalizations is up 70% over the same time period.
Hochul said she made "many, many calls" to individual county government officials, as well as to business leaders, before the mandate took effect.
"73% or so of the New York state population is governed by county leaders who say they support what we're doing here," Hochul claimed.
But some county leaders have questioned why Hochul instituted a statewide mandate for what they called a regional problem. Nassau County Executive-elect Bruce Blakeman said he would not enforce it when he takes office January 1.
"I see that there is no reason to have a mask mandate, and I have indicated that I would not enforce it," he said.
The Long Island is currently fourth of the list of cases in the state, only outnumbered in COVID cases by the Finger Lakes, the Capital Region and Central New York. But Blakeman points out that Nassau's vaccination rate is far higher than elsewhere in the state -- and that Long Island has far more health care facilities.
"We are concerned, but we're not in crisis," he said. "I think we have to use a little common sense. Look at the science. Look at data."
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Suffolk County Executive Steve Bellone said the county will be "educating and informing people," but not enforcing.
"There is no mask police unit, no," he said.
Outgoing Nassau County Executive Laura Curran issued a similar statement.
"Nassau is responding to complaints of violations regarding the mandate, but not actively patrolling to enforce it," she said.
Appearing on morning television, Mayor-elect Eric Adams said he supports the governor's new mandate.
"We are not going to be dragging people off to jail because they are not wearing a mask," he said. "Those outliers who are giving people a difficult time, we will call law enforcement to come and have a real conversation with them. But you will not see people in a harsh, heavy-handed way, policing, to get this issue addressed."
Hochul said 30% of New Yorkers are still not fully vaccinated, and she blamed them for the worsening numbers.
"This is a crisis of the unvaccinated," she said. "Did not have to be. Totally preventable. So if I sound a little frustrated, perhaps I am. This did not have to be the case."
Experts say educating the public about what doctors have said throughout these difficult times -- that the data suggests masks reduce the spread of COVID -- is crucial.
"Masking prevents at least 70% of all transmissions," said Dr. Sharon Nachman, of Stony Brook Children's Hospital. "And I think that's a very valid number."
The state has only seen a 2% of state residents fully vaccinated since Thanksgiving.
The mask rule is in place until January 15, when it will be reevaluated before a determination is made.
MORE CORONAVIRUS COVID-19 COVERAGE
New York City COVID-19 Vaccine Tracker
New Jersey COVID-19 Vaccine Tracker
Centers for Disease Control and Prevention on coronavirus
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