Boston mayor Michelle Wu announced Monday that the city will require proof of vaccination for indoor recreational activities and will tighten the vaccine mandate for city workers.

The moves are intended to tamp down the city's winter surge of COVID-19 cases and the threat of the emerging omicron variant.

Beginning Jan. 15, people aged 12 and up looking to patronize venues like gyms, restaurants and museums will have to present proof of at least one vaccination dose for access. The following month, everyone aged 12 and up will need to present proof of vaccination through an app, a CDC vaccination card, or photo of a vaccination card, or other official immunization record.

Children ages 5-11 will be phased into the new requirements on a slightly extended schedule and won't have to provide proof of first vaccination doses until March 1. Then, beginning in May, children will need to show proof of full vaccination.

A spokesperson for Wu said the city is still developing its own vaccine verification app. According to the city website, other vaccine verification apps will be acceptable ways to show proof of vaccination.

"Vaccination is the most powerful tool we have to fight this pandemic," Wu said, unveiling the new policies from City Hall. "Our essential workers have been on the front lines of fighting this pandemic for more than 650 days and it's time for Boston to follow the science and public health data to ease their burden, to take the big steps that we can to help close vaccination gaps."

As of last week, Boston’s public health commission reported 464,610 residents, or about 68 percent, are fully vaccinated, meaning about a third of the city's population will be unable to access such activities in the new year. Boston averaged more than 350 positive COVID tests per day over the past week; the city's goal is to have fewer than 68.

At the same time, city workers, who are currently allowed to avoid vaccination by submitting to weekly tests, will no longer have that option unless they qualify for a medical or religious exemption.

Wu said 90 percent of Boston's workforce of about 18,000 has already been vaccinated under the current policy.

"This is a response that is rooted in science and public health and we need to take every available action to protect our city's residents, businesses and institutions," Wu said of the testing elimination.

Hours before the press conference began, a group called Boston First Responders United sent an email decrying Wu's move as one that, among other things, should be negotiated through organized labor channels.

As the mayor's press conference got underway, several dozen protesters purporting to represent Boston's first responder community sang the national anthem and yelled various chants in the City Hall entryway, drowning out much of Wu and other elected officials' remarks from the podium.

"Welcome to the people's building," Wu said with a smile as the protesters' chants echoed through the halls. "I just want to emphasize, there is nothing more American than coming together to ensure that we are taking care of each other," she said to applause.

The chants continued through the mayor's press conference, forcing Wu to resort to taking press questions through inquiries whispered into her ear by individual reporters. Republican gubernatorial candidate Geoff Diehl later circulated a photo of himself with the protesters, saying that the new vaccine mandate is a violation of peoples' civil rights.

Wu's announcement appeared to be the first step of a coming domino of Mass. municipalities enacting similar requirements.

Mayors Kim Driscoll of Salem, Breanna Lungo-Koehn of Medford, Sumbul Siddiqui of Cambridge and Joseph Curtatone, Mayor of Somerville all issued statements vowing to take up the issue of expanded vaccine requirements within their cities and towns.

At the press conference Monday, Curtatone appeared alongside Wu and offered an indirect critique of Gov. Charlie Baker, who implemented a vaccine mandate limited to Executive Department workers in October and has resisted re-implementing a state-wide mask mandate amid a winter surge.

"When the state abdicated its responsibility and it fell on deaf ears — our call for regional approaches — we did what we needed to do," Curtatone said. "I am sick of the phone calls I get," he added, pointing to business owners and grieving residents impacted by COVID-19.

Wu's announcement comes amid a broader tightening of vaccination requirements across the state and elsewhere.

The state's Department of Correction recently dismissed 60 workers who failed to comply with the vaccine mandate set forth by Gov. Charlie Baker earlier this year.

The Baker administration, according to MassLive, has not responded to questions regarding how many other Executive Department employees — including agencies like the Department of Public Health and the Massachusetts State Police — have been fired over failure to comply with the state's mandate.