BOSTON (AP) — Customers at Boston's restaurants, gyms and sports arenas had to show proof on Saturday that they were at least partially inoculated against COVID-19 as the city launches a new policy to curb the virus' spread.

The vaccine requirement, announced last month, follows similar orders in New York City, Chicago, Philadelphia and other cities that have moved to exclude people who are unvaccinated from a variety of indoor businesses.

"The best tool we have to end the ongoing COVID surge, reduce hospitalization rates and save lives is for everyone to get vaccinated,” Boston Mayor Michelle Wu said Saturday. “We are putting this measure in place to help safeguard our residents, our businesses and our community."

Boston's requirement is being called B Together and requires customers and workers at many businesses to prove they have had at least one dose of a COVID-19 vaccine. It applies to a range of indoor locales including restaurants, bars, movie theaters and music venues.

Valid proof of inoculation includes a vaccine card or a photo of it, or the newly launched Massachusetts digital vaccine card.

The policy applies to some of the city's biggest venues, including TD Garden, home of the Boston Bruins and Boston Celtics. Amy Latimer, president of TD Garden, said the venue is “in full support of Mayor Wu’s B Together vaccination mandate.”

“We are hopeful, as we continue to work together through these new requirements, that we are making continued progress in the fight against COVID-19,” Latimer said in a statement.

Wu said the policy is needed to help fight a wave of cases driven by the omicron variant.

As of Jan. 10, Boston's positivity rate was almost 32% and the city was averaging 2,500 new cases per day, a 16% increase over two weeks before. More than 80% of residents have received at least one dose of a coronavirus vaccine.