All 50 states have legislation requiring specified vaccines for students. Although exemptions vary from state to state, all school immunization laws grant exemptions to children for medical reasons. There are 44 states and Washington D.C. that grant religious exemptions for people who have religious objections to immunizations. Currently, 15 states allow philosophical exemptions for children whose parents object to immunizations because of personal, moral or other beliefs. Many states align their vaccine requirements with recommendations from the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices. At this time, no state requires children to receive the COVID-19 vaccine for school entry. source
So the only universally applied exemption is for medical reasons. Then there are the religious and philosophical objections. And that's in America. But you're right: I should have said "most of us" instead of "everyone". Fortunately "most of us" has been enough to eradicate past causes of mass deaths.