A measles outbreak in the United States has been festering for some time, with some areas of the country seeing spikes in new cases, doctor visits, and even hospitalizations. There are a handful of areas in the northwest that have been hit the hardest, and Seattle’s public school system has made the tough decision to actually ban students who have yet to be vaccinated against measles.

In the interest of public health and a desire to keep the school system from becoming a haven for the spread of measles, students who have not been immunized against measles are being asked to attend one of the free immunization clinics. Clinics are open Monday through Friday, offering plenty of opportunities for unvaccinated students to get the shots they need.

The school system is maintaining records of who is and who isn’t vaccinated. If parents choose to allow their children to remain unvaccinated through the holiday break, they’ll be asked to keep their students home rather than letting them attend school. According to local news reports, there are roughly 2,000 students with outdate records that need to be cleared up.

“We are doing everything we can here — at this sprint to the finish line — to get as many students up to date as possible,” Tim Robinson, spokesperson for Seattle Public School, told KCPQ. “We don’t want anybody missing out on any educational time.”

If parents decide they still want to hold their children back from being vaccinated, the school district says that any days they miss due to the ban will be treated as unexcused absences.