State Immunization Policy Overview



The Centers for Disease Control and Prevention (CDC) ranks vaccination among the most significant public health achievements of the 20th century. Vaccination, or immunization, saves the lives of 2-3 million children per year worldwide. Childhood vaccination rates in the United States were at approximately 95% for the 2019-2020 school year, the CDC’s recommended target. There are twenty states that exceeded the 95% coverage rate that school year.

Compared to successful childhood vaccination efforts in 2019, there were substantial decreases in routine childhood vaccination rates in 2020 due to the COVID-19 pandemic. Emergency orders requiring or encouraging people to stay at home, as well as school closures and confusion or concern about the safety of doctor visits contributed to this decrease. As social distancing and other prevention policies developed, CDC, state health agencies and other public health officials published guidance on routine childhood vaccines for patients and providers.

As COVID-19 vaccination planning and implementation evolve in 2021, state policymakers have been supporting vaccination efforts by identifying policies that may remove barriers and streamline access to the COVID-19 vaccine. To learn more about state legislative efforts around COVID-19, please visit NCSL’s COVID-19: State Health Actions webpage.

Like many public health programs, immunization programs are invisible when they are working well. High vaccination coverage rates and low incidences of diseases indicate a successful immunization program. Measles outbreaks or emerging viruses like COVID-19, however, serve as reminders of the important role immunization plays in the public health system. 

The federal government partners with state, local, tribal and territorial vaccine programs to finance, administer and track childhood vaccination. While states primarily focus on childhood vaccination, adult vaccination is still a priority for certain age groups and populations. 

School Requirements

From the time they are born, children receive numerous immunizations; there are 16 different recommended vaccines for children 0-18, some requiring multiple doses. The Advisory Committee on Immunization Practices (ACIP) recommends vaccine schedules for children, adolescents and adults based on scientific evidence and the benefits of preventing infectious diseases.

School and day care immunization requirements serve as a safety net for children who do not receive their recommended immunizations as an infant or small child. Authority to add vaccines to school requirements rests with the states and usually reflects the recommendations of ACIP. It is important to note that some states give the state health officer or department of health the authority to change school requirements through administrative rule, such as in Wyoming. Other states revise school vaccination requirements through a combination of rules and legislation or strictly by legislative action. In Illinois, the legislature changes or adds new statute to add a vaccine to the required list for school attendance. Regardless of the process, the state legislature plays an important oversight role in these systems.

School requirements are not without controversy, however. Some parents and advocates contend that vaccine mandates infringe on a person's individual right to choose, especially if a parent is concerned that vaccines may harm children. Many states have exemption laws to accommodate those who may object to immunization mandates.


Although immunization requirements vary from state to state, all states allow exemptions for medical reasons, and all but five states (California, Maine, Mississippi, New York and West Virginia) grant religious or philosophical exemptions for people who have sincerely held beliefs that prohibit immunizations. Currently, 45 states and the District of Columbia have a religious exemption law and 15 of those states also have a philosophical exemption law. These laws allow parents to claim an exemption based on their personal, moral or other beliefs.

Financing Childhood Immunizations

The vaccination of children between 1993 – 2018 saved $408 billion in direct medical cost and saved other segments of society $1.9 trillion. The price of vaccines has risen steadily over the years and can be a significant investment for state governments or health care professionals in a vaccination program. Factors driving up costs include new vaccines, the rising cost of health care and inflation.

Federal Programs

Federal funds pay for approximately 95% of all publicly funded vaccinations through the following two sources.

The Vaccines for Children Program provides free vaccines for children who are uninsured, Medicaid-eligible, underinsured (if receiving immunizations in a federally-qualified health center or rural health clinic), Native American or Alaska Native. The Vaccines for Children program cost $4.7 billion in 2019.

Section 317 of the Public Health Services Act creates a federal program administered by CDC and provides grants to states and territories, commonwealth trusts and several cities for vaccine purchase and programs such as outreach and disease surveillance. The Affordable Care Act (ACA) reauthorized the Section 317 grant program. Prior to enactment of the ACA, states could purchase only recommended childhood immunizations; however, the ACA authorizes states to purchase recommended vaccines for adults as well. The U.S. Health and Human Services (HHS) secretary can negotiate and contract with vaccine manufacturers, allowing states to receive adult vaccines at a negotiated price and provide these vaccines to certain groups of adults, such as uninsured adults, in their immunization programs.

State Programs

Most states depend primarily on federal resources to purchase vaccines. However, federal programs do not cover all children, so many states supplement these funds. 

Universal Purchase: Ten states (Alaska, Idaho, Maine, Massachusetts, New Hampshire, New Mexico, Oregon, Rhode Island, Vermont, and Washington) have universal purchase policies for public and private insurers. In states or territories with this model, the local government purchases all recommended vaccines for all children, including those who are fully insured. Four other states (Connecticut, Florida, South Dakota and Wyoming) have universal select programs that purchase all recommended vaccines for all children with the exception of one or more vaccines. 

Insurance Requirements: The ACA requires new health plans and insurance policies to provide coverage without cost sharing for ACIP recommended vaccines, such as copayments or coinsurance, for certain preventive services. Preventive services in the law specifically include immunizations recommended by ACIP. Provisions allow for up to a one-year delay for coverage of a newly recommended ACIP vaccine.

Immunization Information Systems

Immunization information systems (IIS) are confidential, electronic systems that contain vaccination histories within a geographic area. Data from IIS can help lawmakers and state health officials identify and address areas with lower immunization rates. While states track immunizations across the lifespan, IIS can help ensure that children who are too young to fall under school vaccine requirements receive the recommended vaccinations at the recommended ages. Electronic registries can help doctors check a child's immunization history through a centralized database, without depending on the parents for a paper record.

All 50 states, the District of Columbia and all U.S. territories have at least one regional or local IIS. From 2017-2019, 95% of children under age six participated in a state or local IIS. The rate for 2016 was 94%.

General Population Immunization

While policymakers often prioritize the immunization of children, there are vaccines and vaccine policies that promote general health and safe vaccination rates across age groups. Unlike vaccination efforts for children, there are fewer requirements for adult immunizations. Instead, states and federal health agencies often employ messaging campaigns and expand vaccine administration authority to health providers to maintain safe vaccination rates for the influenza virus and other preventable illnesses. 

The Adult Immunization Schedule recommended by ACIP is not as extensive as its counterpart for children and adolescents. Although it includes vaccines such as Hepatitis B, tetanus and varicella, these apply only to certain at-risk populations and adults in certain occupations. Most adult immunization policies focus on influenza (flu) and pneumococcal (pneumonia) vaccinations.

The ACA increased insurance coverage for adults with private and public health insurance. HHS also supports adult immunizations through the National Adult Immunization Plan. The plan lists four goals (infrastructure, access, demand and innovate) and suggests actions and priorities for federal, state and local partners to consider for implementation of vaccine policies and protocols.

Influenza Immunizations

CDC recommends the influenza vaccine for everyone age 6 months and over, estimating that between 12,000 and 61,000 people die each year from influenza or its complications. Of these deaths, an estimated 75% involved people age 65 or older in the 2018-2019 flu season. 

Scope of Practice

Another strategy to increase adult immunization rates is to broaden the pool of individuals who can administer vaccines. Physicians and nurses typically give vaccines to adults and children. Over the years, many states have expanded certain health care providers' roles to increase the pool of health care professionals who can give shots in hopes of increasing immunization rates. Although physician assistants and nurse practitioners fall within this category, pharmacists are a recent group to expand their scope of practice to include vaccine administration. Pharmacists have authority to vaccinate in every state. Each state decides the vaccines pharmacists can administer and the age groups they are authorized to vaccinate. Increasingly, state executive agencies, legislatures and boards of pharmacy address pharmacists in COVID-19 vaccination efforts and other facets of the pandemic response.

Vaccine Safety

State and federal policymakers, government agencies, vaccine manufacturers, the medical community and parents all agree on the need to keep children safe and healthy. The federal government and vaccine manufacturers go to great lengths to make vaccines for both adults and children as safe as possible. Vaccines can still cause very rare side effects. Much of the movement to implement more flexible exemption laws stems from concerns about vaccine safety

Federal Programs

Once the medical community begins to use a vaccine, suspected adverse reactions can be reported to the Vaccine Adverse Event Reporting System (VAERS). This system, coordinated by CDC and the Food and Drug Administration (FDA), serves as an early warning system to detect problems that may be related to vaccines. VAERS receives approximately 30,000 reports annually. In addition, CDC works with eight large managed care organizations to run the Vaccine Safety Datalink Project. This system contains the medical and immunization histories of more than 7.5 million people and helps CDC assess whether an adverse reaction is purely coincidental or directly linked to an immunization. 

When an adverse event occurs and permanent side effects result, individuals can file a claim with the federal National Vaccine Injury Compensation Program (VICP). The program provides financial assistance and is designed as a "no fault" system for adverse effects on the Vaccine Injury Table (VIT). Families are granted the presumption that the vaccine caused a child's injury or death, if no other medical cause can be found for a specific list of known vaccine-associated side effects. If an adverse event is not on the VIT, families must prove causality. Funding for the VICP comes from the Vaccine Injury Compensation Trust Fund, funded from an excise tax of $0.75 on every dose of covered vaccine that is purchased.

Thimerosal and Mercury

Thimerosal, a preservative that contains a form of mercury, was used in very small amounts for over 50 years as a preservative in some vaccines and to protect vaccines from bacterial contamination. Some parents, researchers and others have voiced concerns about a potential link between health problems, particularly autism, and vaccines containing thimerosal. According to CDC and the World Health Organization, there is no convincing evidence of harm caused by the small amounts of thimerosal in vaccines, except for minor effects like swelling and redness at the infection site due to sensitivity to thimerosal.

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