ASHEVILLE, N.C. (CBS Local)— A chickenpox outbreak at a private school where many families claim religious exemption from vaccines has grown to the state’s largest in more than two decades.

As of Friday, 36 children have contracted chickenpox at the Asheville Waldorf School, in Ashville, North Carolina, according to health officials. It is the worst outbreak in the state since the varicella vaccine was introduced in 1995.

The school, which enrolls children from early childhood through sixth grade, has one of the highest vaccination religious exemption rates in North Carolina. As of the 2017-18 school year, 110 of the school’s 152 students had not received the vaccine, the Asheville Citizen-Times reported.

North Carolina requires certain immunizations for kindergartners, including chickenpox, measles and mumps, but does allow medical and religious exemptions.

“The school follows immunization requirements put in place by the state board of education, but also recognizes that a parent’s decision to immunize their children happens before they enter school,” the school said in a statement to Blue Ridge Public Radio.

Chickenpox is a “very contagious disease,” according to the Centers for Disease Control and Prevention, and can cause a “blister-like rash, itching, tiredness, and fever.” It can lead to complications like inflammation of the brain, pneumonia and even death.

Health officials warn the best way to prevent becoming infected is to be “fully immunized.”

“Two doses of varicella vaccine can offer significant protection against childhood chickenpox and shingles as an adult,” Dr. Jennifer Mullendore, the Buncombe County Medical Director, said in a statement. “When we see high numbers of unimmunized children and adults, we know that an illness like chickenpox can spread easily throughout the community- into our playgrounds, grocery stores, and sports teams.

Most religions do not prohibit vaccinations but some parents in the U.S. have expressed concerns about potential adverse reactions to vaccines. While there can be some allergic reactions, the medical community recommends vaccines as safe and effective.