New York City lawmakers voted today to require all day care and preschool kids under age 5 to get flu vaccines or face expulsion. The new law, which goes into effect in just 30 days, gives day cares and preschools the authority to exclude a child from their facilities if she doesn’t get vaccinated. Additionally, the school could face fines if they fail to keep up-to-date vaccination records for its young students.

According to CBS News, the Board of Health voted unanimously Wednesday in favor of the law. Each year, children under 5 who attend a licensed day care or preschool will be required to get a flu vaccine before Dec. 31, considered the peak of the flu season.

“A lot of people have a misconception that the flu is just like the common cold and nothing that needs to be worried about,” Dr. Jay Varma, deputy commissioner of the New York City Department of Health and Mental Hygiene, told CBS News. “In fact, flu is common and can be very serious for children under the age of 5.”

The proposal is among several of Mayor Michael Bloomberg’s final health mandates. Bloomberg’s controversial Board of Health, whose members are all mayoral appointees, passed the law on Wednesday. Their previous initiatives included the proposed soda ban and bans on smoking.

“Young children have a high risk of developing severe complications from influenza. One-third of children under five in New York City do not receive an annual influenza vaccination, even though the vaccine safely and effectively protects them against influenza illness,” the Health Department said in a statement. “This mandate will help protect the health of young children, while reducing the spread of influenza in New York City.”

Not everyone is thrilled about the new vaccine requirement. Even before the decision was announced, the proposal drew the ire of critics who say the vaccination mandate is an overreach of the board’s power. They point out that mandating flu vaccines for children is extremely rare; currently, only two other states, Connecticut and New Jersey, have such requirements on the books.

“The Bloomberg administration is wildly exaggerating the benefit of the flu shot and we think they are wildly underestimating the risks involved with it,” John Gilmore, the executive director of the Autism Action Network, told the New York Observer. “There are risks associated with every medical procedure.” He went on to cite allergic reactions and exposure to toxic mercury, which is used as a preservative, as just a few of the possible adverse side effects of the vaccination.

Children in New York are already required to get a number of vaccinations before enrolling in school, including for diphtheria, tetanus, pertussis, poliomyelitis, measles, mumps, rubella, varicella, hepatitis B and haemophilus.

While the new law provides certain exemptions, as in the case of religion, it does not provide an out for parents who oppose having their kids vaccinated for flu on philosophical grounds. Even those whose religion prohibits vaccination may have to provide documentation from a religious figure.

Other exemptions will be made for children who have an allergy to the vaccine, “as certified by a physician licensed to practice medicine in this state,” the law reads.