(NewsNation Now) — State and local governments across the country are reinstating safety measures to deal with the highly transmissible omicron variant.

 Here’s how some major cities and states are taking precautions.

Washington, D.C.

Washington Mayor Muriel Bowser on Monday reinstated an indoor mask mandate beginning Tuesday, Dec. 21 until Monday, Jan. 31. All employees, contractors, and grantees of the District of Columbia government must be fully vaccinated against COVID-19 and must have a booster shot. There will be no test-out option, the mayor said. There was no deadline given for the vaccination guidance.

Chicago

Mayor Lori Lightfoot announced Tuesday that individuals 5 years of age and older will be required to show proof that they are fully vaccinated against COVID-19 to dine indoors and visit gyms or entertainment venues where food or drinks are served starting on Jan. 3. People age 16 and older will need to show identification that matches their vaccination record.

“There’s no denying that we are in a fifth wave of COVID-19,” Lightfoot said.

Lightfoot also ordered businesses to develop and keep records of their protocol for enforcing the vaccine requirement. They’ll also need to prominently post signage of the mandate. If employees are not fully vaccinated, the employer must ensure that they continue to mask when interacting with patrons and provide proof of a weekly negative COVID-19 test.

Chicago has an indoor mask mandate in place.

Boston

Boston Mayor Michelle Wu announced proof of vaccination requirements for restaurants and other indoor venues including gyms and theaters on Monday. People working in those locations will also be required to have received their vaccines. The mandate takes effect on Jan. 15.

“We know that as cases go up, it is necessary to protect everyone who interacts with city government,” said Wu.

Boston is working to develop its own app to show proof of vaccination, similar to other cities.

California

California will require health care workers to get a booster shot of the coronavirus vaccine, Gov. Gavin Newsom announced Tuesday. California already requires health care workers to be vaccinated against the coronavirus, a directive that took effect in September.

Newsom is expected to share more information about the mandate on Wednesday.