A student at a Catholic school in Kentucky has sued the Northern Kentucky Health Department, claiming it violated his First Amendment rights by barring him from playing basketball because he refused to be vaccinated against chickenpox.

The lawsuit, filed last week in Boone County Circuit Court on behalf of the student, Jerome Kunkel, an 18-year-old senior, argues that the action violates his right to freedom of religion. Being vaccinated, it contends, would go against Mr. Kunkel’s religious beliefs as a practicing Catholic, because the vaccine contains “aborted fetal cells.”

The lawsuit came after an outbreak of chickenpox at Assumption Academy in Walton, Ky., prompted officials to send out two warnings in February.

On March 14, the Health Department issued a statement saying that because there had been 32 cases of chickenpox at the school, students who were not vaccinated or already immune could not attend school “until 21 days after the onset of rash for the last ill student or staff member.” The statement also said all school extracurricular events would be canceled.