All parents in Michigan have the choice to vaccinate their kids or not, but some aren't in favor of it.
Those parents can get a waiver that allows them to skip school-mandated vaccines.
Some parents say they don't trust vaccines because they don't think injecting a strain of a virus into their kids is a good idea.
For others, it can contradict their religious beliefs.
Most parents are in favor of immunizing their children.
They don't mind waivers, especially now that the educational requirement has been in place for two years.
Angela Minicuci of the Michigan Department of Health and Human Services says since that was established, the number of parents getting waivers has dropped significantly.
"What we found is a lot of times parents got a waiver because they just didn't have time to go in for vaccines, and while they were at the health department they were able to get one."
That's dropped the number of waivers from just over 20,000 down to about 13,000 this past year.
In order to protect the most kids in schools, it's important to get as many kids vaccinated as possible.
That builds a herd immunity to keep even the ones who aren't vaccinated, whether it's because their family is against it, or because they aren't medically able, safe.
You can find resources and information on vaccinations here.