Anyone heading into New York City for the holiday season could be affected by new COVID-19 mandates announced Monday by Mayor Bill de Blasio.

Starting Dec. 14, all children ages 5 through 11 will be required to show proof of at least one dose of the COVID-19 vaccine in order to enter restaurants and theaters.

On Dec. 27, everyone 12 and older will be required to show proof of two doses of the vaccine.

Pediatrician Dr. John Zaso says younger children have been a group that have been a major source of infection for others in the community.

"While they generally don't get super sick themselves, which is good, they can get sick and spread it to the adults," Zaso says. "By having that - a large group of children starting to become immunized - you're really going to tamp down the spread of this disease everywhere."

Also beginning on Dec. 27, there will also be a new vaccine mandate in effect for all private sector employees in the city.

De Blasio called the new mandates a "pre-emptive strike" due to an uptick in coronavirus cases and concerns over the new variant.

The news came as a surprise to some families who had already planned days in the city. Angela DiChiaro has tickets to Radio City at the end of the month for herself, her mother and her 7-year-old daughter. The adults are vaccinated, but her daughter won't be.

"Everybody is mad about this," DiChiaro says. "To do this mandate right before the holidays, knowing people have tickets and plans based on the mandates that were already previously stated--now you're messing up everybody's plans, and I just see it being a huge inconvenience to not only the patrons but to New York City financially because I think a lot of people are just going to cancel their plans."