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Vaccines for Children

The Development of the Immunization Schedule

Last updated 22 April 2022

In the United States, the first requirement for vaccination of children attending public schools was issued in Massachusetts in 1853. (Duffy, 1978) By the end of the 1800s, most of the states in New England had vaccine requirements for children attending public schools, albeit with some exceptions. Back then, the only vaccine of interest was smallpox, a vaccine developed by Edward Jenner at the turn of the century. Of course, that mandate did not come without evidence behind it. Before vaccination, variolation was the intervention of choice to prevent smallpox. Variolation was risky because it was all about giving someone smallpox in a controlled manner and under the supervision of a physician in order to trigger a milder course of the disease while eliciting a lifelong immune response. Once vaccination became the norm, it was preferred over variolation and eventually replaced variolation.

The next leap in vaccine recommendations and requirements for children attending schools came in 1954, when the Salk vaccine trials showed that the injected polio vaccine was highly efficacious in the prevention of paralytic polio. By 1955, the vaccine was fully licensed and Congress appropriated funds to aid local governments in buying the vaccine. (Anderson, 1955) By 1962, federal law further appropriated funds and directed the Centers for Disease Control and Prevention (CDC) to work with local and state health departments to deliver necessary vaccines to children as appropriate. In 1964, the Advisory Committee on Immunization Practices (ACIP) was created under the US Public Health Service to review the science and evidence of vaccines given to children and to make recommendations on when those vaccines should be given and at what age.

The 1960s and 1970s brought new vaccines on the market. The measles vaccines that were developed as single vaccines in the 1960s were combined with the mumps and rubella vaccines to create the “MMR” vaccine. During this time, the World Health Organization (WHO) coordination of the smallpox eradication program was at its height, with cases of smallpox falling to historically low levels. By 1979, the last reported case of naturally-acquired smallpox happened in Africa. In 1980, WHO declared smallpox eradicated -- a first in human history -- and the vaccine began to be discontinued. (World Health Assembly, 1980)

In the 1980s, vaccines against Hepatitis B, Haemophilus influenzae type b, and pneumococcal vaccines went to market and were recommended for children at different ages. In 1986, the created a system of passive and active surveillance for cases of adverse reactions to vaccines as well as a mechanism to compensate any persons injured by vaccines. As the list of vaccines available grew, the incidence of childhood diseases decreased. That increase in available vaccines began to cause confusion, especially as local and state health boards had different opinions on when to give the vaccines and which children should get them.

It would be well over 100 years after the first vaccination mandate for children in schools that an official “schedule” of vaccination was adopted by the Advisory Committee on Immunization Practices, the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP). Those three groups would issue the first recommended schedule in 1995, . (The DTP and MMR vaccines were combination vaccines for diphtheria, tetanus, pertussis; and measles, mumps, rubella.) Since then, the schedule has been adjusted as new vaccines have been developed (like HPV, meningococcal, rotavirus), taken off the market (lyme, rotavirus, intranasal influenza), or the risk profile for children in the United States changes.

Today, according to the National Conference of State Legislatures (NCSL), “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.” Six states (California, Connecticut, Maine, Mississippi, New York, and West Virginia) do not allow religious or philosophical exemptions from vaccination requirements as of 2021. NCSL also states that the laws and regulations on vaccine requirements in all 50 states and DC follow the vaccine schedule set forth by CDC.


Current vaccine schedules:

Children and Adolescents:





  • ANDERSON O. L. (1955). The Polio Vaccine Assistance Act of 1955. American journal of public health and the nation's health, 45(10), 1349–1350.
  • DUFFY, J. (1978). School Vaccination: The Precursor to School Medical Inspection. Journal of the History of Medicine and Allied Sciences, 33(3), 344–355.
  • National Conference of State Legislatures. States With Religious and Philosophical Exemptions From School Immunization Requirements. Available at: . Accessed on November 10, 2021.
  • World Health Assembly, 33. (‎1980)‎. Declaration of global eradication of smallpox. World Health Organization.