In 1855, Massachusetts became the first U.S. state to require children to receive a smallpox vaccine before attending school.
Notes on verification
Confirmed by multiple independent sources including historical/legal references and the original 1855 statute text ('An Act to secure General Vaccination'). Nuance: Boston had a city-level mandate earlier (1827), but Massachusetts was first at the state level, consistent with the claim.
Sources
- Vaccine requirements and vaccine research highlights - Mayo Clinic (mayoclinic.org)
- https://home.heinonline.org/blog/2021/10/mandates-to-vaccinate-a-brief-history/ (home.heinonline.org)
- https://historyofvaccines.org/getting-vaccinated/vaccine-faq/vaccination-exemptions/ (historyofvaccines.org)
- https://www.kff.org/other-health/state-and-local-policies-on-school-vaccine-requirements-overview-and-current-status/ (kff.org)
- https://amarkfoundation.org/reports/do-vaccine-mandates-work/ (amarkfoundation.org)