The school will send home any students with flu or cold-like symptoms that do not have proof of negative pertussis test results or completed pertussis treatment when classes resume after the long weekend Tuesday, as the number of students with whooping cough across both campuses reaches 23.

Students with symptoms are required to be tested for whooping cough via County of Los Angeles Department of Health policy, Head of Upper School Laura Ross and Head of Middle School Jon Wimbish said in an email to students and parents.

A doctor’s note stating proof of vaccination will not be sufficient to prove that a student does not have whooping cough, the email said, and families must provide proof of test results or treatment.

“We hope that you will do your part to stop the spread of pertussis in the community and to minimize any loss of school time for your child,” Ross and Wimbish wrote in the email.