School and health officials say they're worried about the number of students seeking exemptions from state vaccination requirements.
Nurse immunization consultant Dana Greenwood of the state health department says the exemptions make it difficult to achieve what's known as "herd immunity." That occurs when the majority of a school is vaccinated, which makes it less likely that those who aren't will get sick.
Medical waivers are granted for those who are allergic to one or some of the shots or who have weak immune systems and can't tolerate the weakened viruses or antibiotics used in vaccines.
Another exception is for students with religious objections to vaccines.
Students who don't have a waiver can be barred from school until their vaccinations are current.