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NEW YORK (PIX11) – Measles is a highly contagious disease and can spread easily through the air, and appears to keep spreading in New York City.

On Tuesday, the number of measles cases went up yet again.

There are 21 cases total now — 10 pediatric cases and 11 adult cases, according to the city’s Health Department. The outbreak. according to remains centered in Northern Manhattan, but a case was reported in Brooklyn and other cases in the Bronx.

The cases in New York City range from three months to 63 years old. A majority of the children were too young to be vaccinated or within the 12-15 month window when vaccination is recommended.

According to the NYC Department of Education, state law requires that children be immunized against infectious diseases in order to attend school.

Parents may request an exemption for either religious or medical reasons.  Such requests are scrutinized very carefully and permitted only when standards for exemption are met.  Students with exemptions make up about 0.2% of the DOE population.

Children without an approved exemption should be excluded from school.  If a child has an exemption, the student will not be permitted to attend school, if another child is ill with an immunization preventable illness, according to the DOE.

For example, if a classmate of a child with a religious exemption develops measles, the child with an exemption will be excluded from school for a few weeks, according to the DOE.

Of the adults infected, many thought they had been vaccinated, but lacked documentation, the NYC Health Department said.

The NYC Health Department tells PIX11 News that no person has gotten sick with measles from being exposed to a contagious measles patient at a hospital, but the Health Department said to call a doctor immediately if you suspect you have measles before leaving to avoid exposing others.