NEW YORK (AP) — Mayor Bill de Blasio says all New York City employers will have to mandate COVID-19 vaccinations for their workers by Dec. 27.

De Blasio said Monday that the new mandate is aimed at preventing a spike in coronavirus infections during the holiday season and the colder months.

He called it a "preemptive strike" to "stop the further growth of COVID."

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.

The news comes after eight omicron cases were identified in the state on Saturday.

The omicron variant has now been identified in Hawaii, Minnesota, California, and Colorado.

The Minnesota case was a man who had traveled from New York City to attend the Anime NYC 2021 convention at the Javits Center from Nov. 19-21.