Several hundred students in Gary, Indiana, have not been allowed to attend classes this week because they are not up to date on immunizations.

The turn of events began last summer when the Indiana State Department of Health mandated all school children receive three new vaccinations to prevent illnesses such as chicken pox and meningitis. Most school districts in Indiana, including Gary, required students to get the shots before the start of the school year in late August. But three months after the start of school, more than 700 Gary students still lacked the necessary vaccinations. That’s despite the fact that parents received several mailed notices on the shot requirements and the district delayed its own deadline several times. As a result, those students were not allowed to attend classes beginning this week.

“There have been a lot of resources that have been offered on the state level and local health departments and local school corporations,” says Jennifer Dunlap, a spokeswoman with the state health department. “I know they have gone above and beyond in trying to get kids vaccinated.”

Dunlap says each school district sets the vaccination deadline, not the department of health. She says the department does not suggest children miss school unless an illness outbreak happens, though she doesn’t question Gary schools’ move to get children vaccinated.

A spokesman for the Gary schools says the district is offering free immunization clinics this week to get the students caught up and back in school. The clinics are being done in conjunction with the Gary Health Department.