https://www.americanbar.org/groups/litigation/committees/childrens-rights/articles/2019/summer2019-vaccination-law-101-a-guide-for-childrens-lawyers/
Philosophical exemptions. Philosophical exemptions are also known as personal belief exemptions, and they are treated similarly to religious exemptions. About a third of states currently provide for philosophical exemptions, though this number, too, is expected to decline due to recent outbreaks. This exemption is for individuals who hold a conscientious objection to vaccines, including moral, ethical, and personal beliefs.