Who Decides Which Vaccines Americans Should Get and When?
The Advisory Committee on Immunization Practices advises the CDC on how to use licensed vaccines—and the CDC usually listens.
Most Americans are used to being advised by their doctor when they should get a vaccine, how many doses, and at what age.
Less familiar, perhaps, is the group of experts who help the CDC make those calls that doctors and patients rely on. The Advisory Committee on Immunization Practices (ACIP) develops recommendations on how vaccines are used in the United States, such as advising that older adults get a COVID vaccine booster, or that everyone over 6 months of age get the flu shot, or extending eligibility for the HPV vaccine up to age 45.
“Most of the recommendations that you hear about vaccine use come from an ACIP recommendation,” explains Ruth Karron, MD, professor in International Health and founding director of the Johns Hopkins Vaccine Initiative, who has served on the committee.
But what exactly is ACIP? Who sits on this committee, how are members chosen, and how do they make decisions?
What is ACIP?
ACIP is a group of experts that advises the CDC about how vaccines are used in the United States, including who should get the vaccine and at what dose, age, and interval.
ACIP does not advise on which vaccines to license—that is the job of another committee, the Vaccines and Related Biological Products Advisory Committee (VRBPAC), which makes recommendations to the FDA. Once the FDA licenses a vaccine, ACIP will make its recommendations at one of at least three annual meetings.
The group’s 19 voting members include independent medical and public health experts who do not work for CDC, such as academics or employees of public health departments, and one consumer representative. Other nonvoting members include representatives from federal agencies, insurance and pharmaceutical trade associations, and medical groups such as the American Academy of Family Physicians, who offer expertise and guidance.
ACIP members meet in publicly streamed sessions at least three times per year, and “itʼs always a packed agenda,” says Karron.
Following the Data
ACIP considers a number of factors when developing a vaccine recommendation, including the safety and effectiveness data for specific age groups, the quality of available data, the balance of the risks of the vaccine compared to the severity of the disease it targets, how many people stand to benefit from the vaccine, and practical considerations about the feasibility of deploying the vaccine.
ACIP makes recommendations not only for new vaccines, but for updates to existing protocols. For example, in 2024, the group recommended lowering the age for routine pneumococcal vaccination from 65 to 50. They advised this change after reviewing data that showed risk for the disease increased substantially after age 50 and that rates of invasive pneumococcal disease peaked at younger ages in Black patients as compared to white patients.
“For a lot of these recommendations, it's not one and done,” says Karron. “The CDC continues to review evidence as it accrues to be able to use the best evidence to recommend vaccines to protect Americans.”
The Vaccines for Children Program
The CDC almost always follows ACIPʼs advice, but it is not binding—with one important exception: their recommendation on which vaccines should be given at no cost to children whose families may not be able to afford them.
The Vaccines for Children Program is a federal program which, since 1994, has paid for vaccines for children up to age 18 who are Medicaid-eligible, uninsured, or underinsured, or are American Indian or Alaska Native.
“If ACIP votes on a vaccine being covered by VFC, then it has to be paid for,” says Daniel Salmon, PhD ’03, MPH, director of the Institute for Vaccine Safety and professor in International Health. “Thatʼs a really big deal because VCP pays for about half of pediatric vaccines in the United States,” including immunizations for COVID-19, influenza, measles, mumps, rubella, and others.
ACIPʼs recommendations also have important implications for insurance coverage for immunizations. “Insurance companies don't start covering costs based on FDA licensure. They start covering costs based on CDC recommendations,” says Karron.
How Members Are Vetted
To avoid conflicts of interest, ACIP members undergo a vigorous vetting process including financial disclosures and review of previous work on clinical trials.
Members can self-nominate or be nominated, and are chosen based on their clinical training and expertise and their knowledge of vaccines and immunization. Final selections are made by the secretary of the U.S. Department of Health and Human Services.
ACIP members typically serve four-year overlapping terms. They are not paid for their work but receive reimbursement for expenses related to the committee, such as travel.
To prevent conflicts of interest, ACIP members must recuse themselves from votes and discussions on vaccines they are studying, or on any other vaccines manufactured by companies that fund their research.
This vetting process is especially important because ACIP members are responsible for deciding how billions of dollars in federal vaccine funds are spent, says Salmon.
Annalies Winny is a writer and producer at the Johns Hopkins Bloomberg School of Public Health.
