UPPER MARLBORO, Md. (AP) — More than 400 students in Prince George’s County were barred from returning to school Nov. 5 because they hadn’t gotten their vaccinations.

A spokesman for Prince George’s County Public Schools siad 414 students still had not been vaccinated as of Oct. 31. Students were off of school Monday and Tuesday for teacher training and Election Day.

Schools spokesman Max Pugh Jr. said parents of those students have received exclusion letters telling them their children won’t be allowed at school Wednesday unless they arrive with proof of immunization or signed exemption letters.

He said non-compliant students arriving at school would have to be picked up by a parent or guardian.

The school system has said it offered frequent opportunities for students to get vaccinated, including free immunization clinics on weeknights and weekends.