STUDIO CITY (CBSLA) — An exclusive private school has been hit with dozens cases of whooping cough, which has sickened a large number of teenagers across Los Angeles County.

Health officials say they are monitoring three large clusters of highly contagious whooping cough among 11- to 18-year-olds. The county Department of Health issued a health alert to pediatricians and other health care providers about the uptick in whooping cough last week.

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Harvard-Westlake’s Studio City campus. (credit: CBS)

Harvard-Westlake, which has campuses in Studio City and Beverly Crest, was hit particularly hard, with 30 students coming down with whooping cough since November, according to the Hollywood Reporter.

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Of about 1,600 students attend Harvard-Westlake, where tuition is close to $40,000 a year, only 18 opted out of vaccinations for medical reasons. None of the 30 students who contracted whooping cough were not vaccinated.

School officials say they have done all they can to control the outbreak, including sending students home, sanitizing classrooms, and implementing a new protocol that requires students who stay home sick must be tested at a hospital for whooping cough before they can return to class.

Whooping cough, also known as pertussis, gets its name from the distinctive cough that sounds like a whoop. It is highly contagious and can be fatal for infants.

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Parents are being urged to take students with flu-like symptoms to get them tested at a hospital before allowing them to return back to school.