All city employees, onsite contractors and volunteers in Boston will be required to get vaccinated for COVID-19 by October 18 or submit to weekly testing.

Acting Mayor Kim Janey made the announcement Thursday, two weeks after announcing a plan to develop a vaccine mandate for city workers.

“Our purpose is to protect our employees and the public,” Janey said at a City Hall press conference. “And our work is rooted in public health guidance and based on data and science.”

Janey said the announcement comes after weeks of meeting with cabinet chiefs, department heads and labor leaders. The city’s public teachers' union has endorsed the move.

“As the CEO of the largest employer in Boston that employs 18,000 people, we have to do all we can to protect ourselves, our families and the residents we serve,” Janey said.

Workers will be required to enter their vaccination status into an online portal.

“The portal will be designed to protect the privacy of our employees’ health information,” Janey said.

The city is setting up testing locations at City Hall and around the city to help employees who are not vaccinated meet the requirement of getting tested every week.

“When we trust the science, track the data and work together, we can help to keep our city and her residents safe,” Janey said.

Employees at Boston Public Schools, the Boston Centers for Youth & Families, Boston Public Libraries, Age Strong, Commission on Disabilities and other agencies deemed by the city as providing services to “high-priority residents” will be required to meet the new mandate by September 20. Onsite contractors and volunteers in those same agencies must comply by October 4. All other employees, contractors and volunteers have until October 18.

City Councilor At-Large and mayoral candidate Michelle Wu released a statement after Janey’s announcement.

“I’m glad the Administration has finally answered the call to mandate vaccines for city workers—but with the Delta variant surging, we need more than half-measures,” she said. “City Hall must set out regulations on vaccination for high-risk indoor spaces like gyms, salons, and restaurants to ensure protections for all our communities.”

Former Boston chief of economic development and mayoral candidate John Barros also responded to the change, calling it “overdue” and citing that he had called for the same policy nearly two weeks ago.

“This should have been implemented last month when Acting Mayor Janey required employees to come back to City Hall full time,” he wrote. “I urge the Acting Mayor to follow the lead of municipalities like Belmont, Salem, and Provincetown, and businesses like AEG concerts and our local museums in instituting a mask mandate. And if the Acting Mayor won’t lead, I call on Governor Baker to act.”

Janey continues to resist calls for broader proof-of-vaccination requirements, saying that would “lock out” many people in neighborhoods with the lowest vaccination rates.

“We continue to prioritize them when it comes to the vaccine. But to suggest that half of Black residents couldn’t go to a grocery store, I think, is insane,” Janey said. “So instead, we are prioritizing them, meeting them where they are, partnering with our community health centers — with all of the partners who receive the vaccine equity grant.”

Councilor and mayoral candidate Andrea Campbell took issue with Janey following the event.

“The Acting Mayor is once again spreading misinformation about the vaccine by saying that proof of vaccination would be required to shop in a grocery store. No one has suggested that for Boston, and this wasn’t part of the policy implemented in New York City. Misinformation like this erodes trust in our public health system and will likely prevent people from getting vaccinated,” a statement from Campbell read.

When pressed on the fact that her mayoral opponents aren’t suggesting that unvaccinated people should be barred from grocery stores, Janey pushed back.

“Should we get to the point where we need to do that in large venues, then I will absolutely do that.” Janey said. “But what I will not do is politicize the pandemic. I’m going to prioritize people.”