Philadelphia’s long-delayed vaccine mandate for its almost 24,000 unionized city workers, which was to take effect Monday, has been paused indefinitely by an arbitration panel overseeing the implementation of the policy for the Philadelphia police union.

Monday’s decision by the panel halts a process that could have seen noncomplying police officers — and, due to interlocking labor agreements, most other unionized city workers — placed on leave as soon as Tuesday.

It is the latest setback for a policy that Mayor Jim Kenney originally sought to take effect in mid-January only to be delayed repeatedly by labor disputes.

“The mayor has been clear from the beginning that the intent of the mandate was to ensure we are doing everything we can to protect our employees and the individuals they serve,” Kenney spokesperson Joy Huertas said. “To that end, since announcing the mandate we have seen significant increases in the number of employees who have started and completed their vaccination series.”

The city said Monday that 92% of the city’s unionized workforce has either been vaccinated or applied for exemptions.

The panel previously set Feb. 11 as the start date for the mandate, but it also laid out a series of steps that effectively pushed the deadline back to Monday, giving officers until then to get vaccinated or to secure a religious or medical exemption. Officers who still failed to comply by that time would have been placed on leave beginning Tuesday and could eventually have been fired.

But on Monday, the panel paused its own plan, citing a 95% compliance rate among police officers and delays in obtaining additional data.

“The panel is very encouraged by the progress reflected in the updated accounting, including the fact that approximately 95% of the Police Department is either fully vaccinated, has received a first vaccination shot or has submitted a request for a medical or religious exemption,” read the order from the panel, which is composed of one city appointee, one FOP appointee, and a third member who is a neutral arbitrator. “The parties are to be commended on their efforts in this regard.”

The city did not respond to a request for information on how many officers who are in compliance with the policy are vaccinated, and how many have obtained exemptions. An estimate on the city website indicates that 71% to 80% of Police Department employees are vaccinated.

Two other unions representing the city’s nonuniformed workers — District Councils 33 and 47 of the American Federation of State, County and Municipal Employees — have clauses in their own vaccine mandate agreements that delay the implementation of the policy if any other city union secures a later date, meaning that the FOP panel’s decision delayed the policy for all unionized employees.

The only union yet to reach an agreement with the city is Local 22 of the International Association of Fire Fighters, which has publicly opposed the mandate and threatened a lawsuit against the city if its members are forced to comply. The city is scheduled to present its case for the IAFF case before arbitrators on March 7.

A vaccine mandate for the city’s 2,000 nonunionized employees took effect in December, and the city has reported a 99% compliance rate with 13 employees being terminated for failing to get vaccinated or exempted.