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Mayor Bill de Blasio on Thursday declared a state of emergency over the spread of the deadly coronavirus and predicted that New York City would have 1,000 confirmed cases by next week.

“It’s going to get a lot worse before it gets better,” he warned during a City Hall news conference.

The city currently counts 95 confirmed cases of the coronavirus, de Blasio said, up from 42 just since Wednesday.

“These overall numbers are striking and troubling,” he said.

De Blasio declared that New York City’s public schools would remain open despite the outbreak, although extracurricular activities and parent-teacher conferences are either going online or will be canceled.

Additionally, Hizzoner said he would authorize 10% of city employees to work from home and put another 20% on staggered schedules, “as much as possible away from the rush hours.”

The changes will affect up to 100,000 municipal employees.

De Blasio warned that he expects the crisis to last at least six months, with more time needed to recover.

“This will not be over soon. It’s going to be a long, tough battle,” he said.

De Blasio said he agreed with Gov. Andrew Cuomo’s decision to close all places with legal occupancy of 500 people or more — including Madison Square Garden and Barclays Center — and to slash the occupancy of smaller places in half.

De Blasio said he “won’t be surprised” if the move forces some businesses to close, but said, “These are the rules we will enforce from now on.”

“I can assure you, none of us wanted to take this action,” de Blasio said.

“But it is the point where it’s necessary.”