A California high school sent home two dozen unvaccinated students for three weeks as the Orange County area grapples with an outbreak of the measles.

Huntington Beach High School, where a student with a confirmed case of measles was on campus from Jan. 6 to Jan. 8 sent a letter home to parents after checking to see which students were vaccinated and which were not, MyFoxLA.com reported.

“Unimmunized students are excluded from school for 21 days past the date of exposure, during which they need to monitor themselves for signs of measles,” Deanne Thompson, Orange County health care agency spokeswoman said. “This is to avoid spreading the disease.”

While the state of California requires children receive the MMR vaccination shot to protect against measles, mumps and rubella, an exemption may be granted by signing a personal relief waiver.

Thompson said there have been 16 confirmed cases in Orange County, including six that are not linked to the original Disneyland outbreak.

“It is at large in the community now, and particularly infants too young to be immunized, people with other health conditions and, of course, people who aren’t immunized need to be very concerned,” she said.

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