Cook County Health adopts CDC's guidance on universal masking in schools CDC recommends all students wear masks, whether vaccinated or not The Centers for Disease Control and Prevention is recommending that all students in kindergarten through 12th grade wear masks when they return to classrooms. COOK COUNTY, Ill. - The latest guidance from the Centers for Disease Control recommends universal masking in schools and the Cook County Health Department agrees. "Nobody is exempt," said Dr. Rachel Rubin. "Children, adults, guests to schools, unless there's a medical reason that they cannot wear a mask. in which case other mitigation strategies should be in place."