NEW YORK (AP) — All private employers in New York City will have to require their workers to get vaccinated against COVID-19 by Dec. 27, according to Mayor Bill de Blasi.

De Blasio said workers will need to provide proof they have received at least one dose of the vaccine. And they will not be allowed to get out of the requirement by agreeing to regular COVID-19 testing instead.

The measure will apply to roughly 184,000 businesses not covered by previous vaccine mandates, ranging from multinational corporations to mom-and-pop businesses in the city of 8.8 million people, according to a spokesperson for the mayor.

The city’s private-sector workforce is 3.7 million.

“We in New York City have decided to use a preemptive strike to really do something bold to stop the further growth of COVID and the dangers it’s causing to all of us,” de Blasio said. “All private-sector employers in New York City will be covered by this vaccine mandate as of Dec. 22.”

Vaccinations are already required for city employees including teachers, police officers and firefighters, and a vaccination mandate for employees of private and religious schools was announced last week.

De Blasio said he expects the new mandate to survive any legal challenges.

Current New York City COVID-19 rules also include at least one vaccine dose for indoor restaurant dining, entertainment venues and fitness centers. Under new mandates for indoor dining, entertainment and gyms, two shots will be required for people over 12. One shot will be required for children aged 5 to 11, who are not covered by the current mandate, de Blasio said.