NEW YORK (CBSNewYork) — Children who go to preschool or day care in New York City will now be required to get flu shots.

The Board of Health voted unanimously Wednesday in favor of the mandatory vaccine for children under 6 years old. The new rule takes effect in 30 days and will be required for about 150,000 children.

“Because the regulation is being adopted at this current time period, we actually won’t be officially enforcing it until one year from now,” Dr. Jay Varma, deputy commissioner for disease control, told 1010 WINS. “The requirement is that children who are attending a licensed preschool or day care center need to have received their influenza vaccination by Dec. 31 of any given year.”

Connecticut and New Jersey are the only two states in America with mandatory flu shots for children in day care. The measure passed Wednesday by the Board of Health would only apply to New York City and not the rest of New York state.

“We think we can prevent 20,000 to 25,000 kids a year from being sick,” Varma said.

Long Island mother Melody Butler told CBS 2’s Scott Rapoport she wished the measure did extend past New York City. “I am a pediatric nurse and I find vaccines to be one of the greatest inventions we have to protect ourselves,” Butler said.

But some autism advocates strongly oppose the plan. Kimberly Mack Rosenberg has a child on the autism spectrum and isn’t ruling out that a flu shot might be responsible.

“For him, I don’t know if it was a flu vaccine,” she said. “I do believe that his autism was at least partially vaccine mediated.”

Some educators also have reluctance toward the new mandate. “A lot of problems with autism — parents are very scared. I think they should have their choice, whether they want to vaccinate their child or not,” said Carol Schafenberg, principal of P.S. 76 in Long Island City.

Children in day care and preschool are already required to get vaccinated against illnesses such as measles and chicken pox. City officials believe the latest initiative adds another layer of protection for children and those who come in contact with them.

“Children under the age of 5 are at the highest risk of both contracting influenza as well as suffering severe complications,” Varma told WCBS 880’s Marla Diamond. “The only absolute contraindication is a previous severe allergic reaction.”

Parents who are strongly opposed to the initiative could avoid the mandated vaccines by sending their children to a state preschool or day care. Parents may also opt out for medical and religious reasons.

Decisions on exemptions will be made by an administrator at each facility on a case by case basis.

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