CHICAGO (AP) — An arbitrator has ruled that several unions representing Chicago firefighters and other city employees must follow Mayor Lori Lightfoot’s COVID-19 vaccination policy.

The ruling means that the union employees will lose pay if they do not receive a first shot by Dec. 31. They must get a second shot by Jan. 31 if they choose a two-dose vaccine.

The ruling issued Wednesday applies to the Chicago Firefighters Union Local 2, the American Federation of State, County and Municipal Employees, the International Brotherhood of Electrical Workers Local 21, Service Employees International Union Local 73, Teamsters Local 700 and Coalition of Unionized Public Employees.

The ruling does not apply to members of the Chicago Fraternal Order of Police, which has been engaged in a bitter battle with the mayor over the mandate. A Cook County judge suspended the Dec. 31 vaccination deadline for police and sent the issue to arbitration, which begins Dec. 27.

The city’s law department praised Wednesday’s decision, which comes after dozens of firefighters and paramedics who defied the reporting requirement were placed on no-pay status and sent home.

“The City is pleased that a neutral arbitrator selected by both parties upheld the City’s right to issue a vaccine mandate to its employees,” a spokeswoman with the law department said, according to the Chicago Tribune. “The arbitrator further upheld the City’s right to place employees who do not become vaccinated by the deadline in a no-pay status.”