A Suffolk Superior Court judge rejected three first responder unions' request to stop Boston's revised COVID-19 vaccination policy from taking effect on Saturday.

Mayor Michelle Wu announced the policy change last month. It requires visitors present proof of vaccination for entry to most indoor recreation venues. It also requires all municipal employees provide evidence that they have received at least one dose of vaccine by Saturday, unless they qualify for a medical or religious exemption. This is the item of concern to the unions, and what is popularly referred to as the vaccine mandate.

Lawyers for the Boston Police Superior Officers Federation, the Boston Police Detectives Benevolent Society and the Boston Firefighters Union Local 718 argued in a virtual hearing that the new policy violated a previous agreement that allowed workers willing to take a weekly coronavirus test to be exempt from vaccination.

Speaking from the bench, Judge Jeffrey A. Locke said the unions had good arguments, but not good enough to prevail given the state of the pandemic.

"I will not enjoin the enforcement of the policy as of Jan. 15 because I think that the public health emergency now is of such a nature that it outweighs the competing claims of harm," he told attorneys, vowing to flesh out his reasoning in a written opinion.

"I make that determination," Judge Locke continued, "with the highest respect for the three plaintiff organizations who have been the lifeline of the city of Boston and of the commonwealth throughout this pandemic."

The suit sought to relieve more than 400 combined members of the three unions of an obligation to get a COVID-19 vaccine. The majority of the unvaccinated union members — 353 people, lawyers said — are firefighters.

Overall, about 16,670 of the city’s 18,000 employees were fully vaccinated as of Monday, according to the city press office. Since the policy announcement last month, about 100 additional employees have submitted proof of a first dose of a COVID-19 vaccine.

Workers who do not comply with the policy by providing evidence of a first dose or requesting an accommodation by this weekend will be notified of their noncompliance and placed on administrative leave pending discipline.

Patrick Bryant, attorney for the Superior Officers Federation, noted Locke's respect for the arguments raised in the hearing.

"We're heartened that he appeared to confirm our concerns about the city's disregard for collective bargaining obligations, and yet are still disappointed he did not grant the temporary relief we sought," Bryant said in a statement. "We are reviewing our options."

The union issued its own statement Wednesday night, criticizing Mayor Wu.

"We are nothing less than disappointed and disgusted with your blatant disregard for fair labor, our rights, and the safety of all City of Boston residents," the group said.

Wu has endured criticism, sometimes racist and vitriolic, in the days since announcing the revised policy that applies to Boston's 18,000 municipal workers.

On the day of the hearing, a small band of anti-vaccine mandate protesters gathered outside Wu's Roslindale home to express their displeasure.

Bryant said the unions will take their case to the city's Department of Labor Relations, where in the coming months it is expected to move to arbitration.