St. Paul Mayor Melvin Carter on Thursday rolled out one of the state's most stringent COVID-19 vaccine policies with an announcement that nearly every city employee will be required to have their shots completed by the end of the year.

"Since testing only provides a way to determine if someone has COVID after they've already contracted it, offers no protection for an unvaccinated individual, nor for any individuals they interact with, our vaccine requirement will not include an opt-out for testing," Carter said in an e-mail sent to nearly 4,000 city workers.

St. Paul will make exceptions for those who qualify for medical accommodations or religious exemptions, but others who do not comply with the mandate "will not be able to work and may be subject to discipline," Carter spokesperson Peter Leggett said.

Union leaders have warned this could lead to staffing shortages in departments already stretched thin by pandemic-fueled budget cuts.

"My members want the choice of what they put in their body," said Mike Smith, president of St. Paul Firefighters Local 21. He said between 30 and 80 firefighters could be forced to leave their jobs if they are not granted an exemption.

Similar disputes are already playing out in cities across the country that have implemented vaccine mandates without a testing option. More than 150 police and fire employees in Seattle will likely not be allowed to work for at least a month while the city considers exemption requests, according to the Seattle Times. At least 46,000 city workers in New York will soon lose their paychecks if they do not comply with the mayor's Nov. 1 vaccination deadline, the New York Times reported.

But the mandates have also proved effective at increasing vaccination rates. According to the Denver Post, 99% of 10,000 municipal workers complied with the city's requirement or received an exemption before an Oct. 1 deadline.

"Amid our ongoing work to rebuild, we continue to hear from public health professionals, including our Minnesota Department of Health and the [Centers for Disease Control and Prevention], that the best way to prevent infection and reduce the spread of COVID is to get vaccinated," Carter said, pointing to Ramsey County's positivity rate, which has increased threefold since July.

Mark Ross, president of the St. Paul Police Federation, said the city should be testing all workers if health and safety are its biggest concerns, noting breakthrough cases can occur and lead to transmission of the virus.

"We cannot afford to lose one cop in St. Paul over this. And that's our greatest fear — losing a chunk of our workforce," said Ross, who estimates roughly 75% of the city's officers have been vaccinated.

Carter, who is up for re-election in November, has heard concerns about St. Paul's police staffing levels for months as the pandemic has helped fuel a rise in crime. Police Chief Todd Axtell has asked the City Council to allocate $3.1 million more to his department than what the mayor proposed for 2022 to ensure the force is staffed at its full strength of 620 throughout the year.

Dozens of city workers from other departments spoke during the council's outdoor meeting at Como Lakeside Pavilion last week, urging members to ask Carter to consider a testing alternative. Ross and Smith said they and other union leaders refused to sign memorandums of understanding that could waive members' rights.

"Just as they have done throughout the course of this pandemic, our first responders are consistent in putting the safety of our community first, every day. In the face of overwhelming evidence, and the strong recommendation of public health professionals, we are counting on them to do the same to protect themselves, our colleagues, and the entire public we serve by getting vaccinated," Leggett said in an e-mail Thursday.

Council members asked the mayor to explore a vaccine mandate in August, when other state and local government entities announced their vaccine or testing requirements for employees. Though the council previously expressed disappointment at the speed of St. Paul's policy rollout, Council Member Chris Tolbert on Thursday said he was pleased to see the city take this step.

"The only way we're going to get out of this pandemic is to vaccinate our way out of it," he said. "We're not asking anyone to do something that we didn't do."