When Did Vaccines Become Mandatory for Schools?
The first vaccination requirement to attend school in the United States was introduced in the 1850s in Massachusetts, specifically for smallpox vaccine. During the late 19th century, as public health systems developed, similar laws were introduced in other states, largely in response to recurring smallpox outbreaks.
By the early 20th century, many states had enacted school-entry vaccination mandates, and in 1922 the U.S. Supreme Court affirmed their constitutionality in Zucht v. King, ruling that schools could exclude unvaccinated students. Over the course of the 20th century, the list of required vaccines expanded beyond smallpox to include those against diphtheria, polio, measles, and other diseases. By 1980 all U.S. states had implemented laws requiring vaccinations for children attending public schools, a trend that largely solidified in response to major measles outbreaks in the 1960s and ’70s. Limited exemptions were permitted, depending on state law.
Similar measures were adopted in other parts of the world. In Italy, for example, mandatory smallpox vaccination was introduced in 1821–22, and in the United Kingdom the Vaccination Act of 1853 made smallpox vaccination compulsory for infants. Later legislation there introduced penalties for noncompliance, though strict enforcement waned over time. In the late 20th century, the number of countries with school entry tied to proof of immunization increased significantly, such that by 2018, more than 100 countries worldwide had mandatory vaccination policies.
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The scope and enforcement of vaccine mandates for children entering school, however, continue to vary widely across countries. In addition, in the United States trends in vaccine exemptions have been on the rise, particularly for nonmedical reasons, and vaccination mandates have been threatened by political and societal perspectives. In 2025, for instance, Florida, a Republican-led state, announced plans to cancel its vaccine mandates. Other states were also considering rolling back mandates, raising concerns about furthering the spread of vaccine-preventable diseases, particularly those that affect children who are too young to be vaccinated or who have compromised immune systems.