A federal judge has blocked the vaccine mandate that was to come into effect in New York City schools its teachers and other workers in a few days.

Workers in the nation’s largest school system were to be required to show vaccination proof starting on Monday but a judge for the 2nd US Circuit Court of Appeals granted a temporary injunction on the matter late on Friday.

The injunction was sought by a group of teachers. The judge referred the case to a three-judge panel for hearing on an expedited basis.

According to Department of Education spokesperson Danielle Filson, officials are seeking a speedy resolution and that the circuit court has the motion on its calendar for Wednesday.

“We’re confident our vaccine mandate will continue to be upheld once all the facts have been presented because that is the level of protection our students and staff deserve,” The Associated Press quoted Filson as saying.

According to a report by the New York Post, the department sent an email to principals on Saturday saying they “should continue to prepare for the possibility that the vaccine mandate will go into effect later in the week.”

Mayor Bill de Blasio announced in August that about 148,000 school employees would have to get at least a first dose of the COVID-19 vaccination by September 27. The policy covers teachers, along with other staffers, such as custodians and cafeteria workers.

It’s the first no-test-option vaccination mandate for a broad group of city workers in the nation’s most populous city. And it mirrors a similar statewide mandate for hospital and nursing home workers set to go into effect Monday.

As of Friday, 82% of department employees have been vaccinated, including 88% of teachers.

Even though most school workers have been vaccinated, unions representing New York City principals and teachers warned that could still leave the 1 million-student school system short of as many as 10,000 teachers, along with other staffers.

De Blasio has resisted calls to delay the mandate, insisting the city was ready.

“We’ve been planning all along. We have a lot of substitutes ready. A lot is going to happen between now and Monday but beyond that, we are ready, even to the tune of, if we need thousands, we have thousands,” Blasio said on Friday.

(With inputs from the Associated Press)