A private school founded by an anti-vaccination activist in South Florida has warned teachers and staff against taking the COVID-19 vaccine, saying it will not employ anyone who has received the shot.

The Centner Academy in Miami sent a notice to parents on Monday informing them of a new policy for its two campuses for about 300 students from pre-kindergarten through eighth grade. Teachers or staff who have already taken the vaccine were told to continue reporting to school but to stay separated from students.

Co-founder Leila Centner told employees in a letter last week that she made the policy decision with a “very heavy heart,” the Miami Herald reported. Centner asked those who have not received a COVID-19 vaccine to wait until the end of the school year, and recommended holding off until research shows how the vaccine might affect the non-vaccinated.

Dr. Aileen Marty, an infectious disease specialist with Florida International University’s Wertheim College of Medicine, said there is no evidence that unvaccinated people face any risks from the vaccinations of others.

Centner and her husband David Centner started the school in 2019 after moving to Miami from New York. The school’s website promotes “medical freedom” from vaccines and offers to help parents opt out of vaccines that are otherwise required for students in Florida.