(CBS) — There are now three confirmed mumps cases at Barrington High School, and that confirms it as an outbreak.

In a note to parents Tuesday, Lake County and state health officials announced plans to provide a free vaccination clinic.

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Eligible students and staff will receive the so-called MMR — that stands for measles, mumps and rubella – vaccination.

The clinic is expected to open sometime this week.

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Parents are asked to keep their child home from school if they show any signs or symptoms of the disease. Health officials say there are now 34 confirmed, suspected and probable mumps cases.

In Chicago, a spokesperson for Chicago Public Schools says authorities are evaluating a “potential” case of mumps at a North Side school.

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“A diagnosis has not been confirmed, and we will work with the Department of Public Health to institute any necessary precautionary measures,” a statement said.