(Bloomberg) -- New York City issued a new mask advisory on Monday, “strongly recommending” residents wear masks in all indoor locations regardless of vaccination.

The health advisory stops short of a mandate but signifies officials’ trepidation of a new Covid-19 wave as the omicron variant spreads around the world and New York sees an increase in post-Thanksgiving Covid cases.

The city said there were no confirmed cases of the variant, which was identified in Botswana and South Africa and poses a “very high” risk, according to the World Health Organization, which added it to its list of variants of concerns. Still, New York City Mayor Bill de Blasio said the city was “carefully watching the situation” and was coordinating with New York Governor Kathy Hochul on the virus response. 

“We’re going to be in a very vigilant state in the meantime and taking any and all actions as we get facts to support them,” de Blasio said at a briefing Monday.

The city also announced a new vaccine mandate that requires childcare workers to get the shot ahead of a Dec. 20 deadline. The mandate will impact around 100,000 childcare and early intervention programs citywide.

The threat of omicron comes as New York City may already be seeing signs of a winter spike. The city’s positive test rate rose to a two-month high as hospitals admitted more than 100 new virus patients on Friday, contributing to a 25% jump in hospitalizations in just two weeks.

Cases across the state have also climbed. Hochul late last week declared a state of emergency to allow the health department to limit non-essential, non-urgent procedures at hospitals and acquire critical supplies more quickly. She also ordered nursing homes and adult-care facilities to make boosters available to all residents.

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