ASHEVILLE (AP) — Health officials in Buncombe County are notifying families about a chickenpox outbreak at a local school.

The Asheville Citizen-Times reports Dr. Jennifer Mullendore, medical director for Buncombe County Health and Human Services, says at least seven people have become sick at the school since the beginning of February. Mullendore said the agency is not identifying the school.

Mullendore said the agency is working with the school to notify families of students and staff. They must provide proof of immunization or risk being held out of school for 21 days.

Neither Asheville City nor Buncombe County school officials report chickenpox outbreaks in any of their schools.

The Centers for Disease Control and Prevention says chickenpox is highly contagious and causes a “blister-like rash, itching, tiredness and fever.”