RFK's handpicked advisers are coming for the childhood vaccine schedule. Here's what to know.

An influential Centers for Disease Control and Prevention (CDC) vaccine advisory committee that has been reconstituted by Health and Human Services Secretary (HHS) Robert F. Kennedy, Jr. will meet Thursday and Friday (Sept. 18 and 19) to discuss changes to the childhood vaccine schedule.

These changes, experts say, could make American children less healthy.

The Advisory Committee on Immunization Practices (ACIP) meeting starting Thursday will focus on the hepatitis B vaccine, as well as the MMRV vaccine — a version of the measles, mumps and rubella (MMR) vaccine that also protects against varicella, or chickenpox. The first dose of the hepatitis B vaccine is currently recommended at birth, while the first dose of the MMRV vaccine is recommended at age 12 to 15 months.

The discussions being raised by the ACIP are alarming outside experts, who say there is no new data suggesting these recommendations are problematic — and that the current schedule is well studied and highly effective at preventing these dangerous infections.

"It's brilliantly successful," Dr. William Schaffner, a professor of preventive medicine at the Vanderbilt University School of Medicine, said of the recommendation to vaccinate everyone against hepatitis B at birth. Schaffner an ACIP member in the 1980s and was a liaison to the committee for various organizations between 1986 and 2024. "If we change it, we will start to see transmissions again," he said.

Hepatitis B protection for infants

Kennedy is the founder of Children's Health Defense, a nonprofit known for campaigning against childhood vaccines, and he stepped down as chairman of the group prior to assuming his role at HHS. In June, he fired the 17 sitting members of the ACIP and has since replaced them with new members, some of whom rose to prominence by promoting unproven treatments for COVID-19 and criticizing universal vaccination against the disease.

The two routine childhood shots that the committee will vote on this week are not new. The MMR vaccine was first licensed in 1971, and the MMRV vaccine, which adds chickenpox protection to the same shot, was approved in 2005. The hepatitis B vaccine has been recommended to newborns for over 30 years, starting in 1991.

Vaccination immediately after birth protects infants from contracting the virus from their mothers upon delivery. That's because the virus spreads through bodily fluids — including blood, saliva, menstrual, vaginal and seminal fluids — and can pass to babies in the birth canal.

Hepatitis B is a viral infection that can become chronic, especially for people who are infected as infants. It can easily go undetected, causing liver damage and raising the risk of liver cancer. Once chronic, it's a permanent infection that requires antivirals and shots to manage, and it can lead people to need liver transplants. Mothers are screened for the infection, but their cases sometimes go undetected and this puts babies at risk, Higgins said.

On Tuesday (Sept. 16), former CDC officials told KFF Health News that the ACIP is likely to recommend pushing out the vaccine to age 4.

"What you're going to hear tomorrow is an argument that we can identify these mothers who are positive and vaccinate their babies early and wait til the others get a little bit older before we vaccinate them," Schaffner said. "We tried that. It did not work."

"Those kids that fall through the gaps," he said, "they're now at risk for infection and subsequent liver damage, cancer and death."

Anti-vaccine advocates argue that the shot is not necessary for newborns because hepatitis B infections in adults often spread via intravenous drug use or sexual activity. But before newborn vaccination was introduced, there were about 18,000 cases of hepatitis B in children under 10 in the United States each year, Higgins said. In about half of those cases, the source of the infection was unknown. Kids can pick up the virus via contact with even tiny amounts of blood, such as from a scraped knee, a shared toothbrush exposed to bloody gums, or a toddler biting incident at daycare.

By comparison, in 1990, there were three new cases of hepatitis B for every 100,000 children and adolescents in the U.S., according to CDC data. By 2002, that number had dropped to 0.3 out of every 100,000. Today, it sits below 0.1 per 100,000.

The benefits carry on to adulthood: Because the vaccine induces long-lasting protection, rates of hepatitis B in people ages 30 to 39 years — the first to be vaccinated as infants — show a steep decline after 2015.

"The downside of this is minimal to none," Dr. Michelle Barron, senior medical director of infection prevention and control for the UCHealth hospital system in Colorado, told Live Science. "The vaccines are safe."

The MMRV vaccine

Per the current vaccination schedule, children get their first dose of either the MMRV, or the MMR along with the chickenpox vaccine, between the ages of 12 and 15 months. A second dose comes between 4 and 6 years old and typically provides lifelong immunity to the infection.

Within three years of the introduction of the MMRV shot, researchers noted an increased risk of febrile seizures, or seizures brought on by fever, in kids who got the MMRV vaccine rather than the MMR and chickenpox shots separately. According to the CDC, the risk of seizures is twice as high from MMRV than for the MMR in kids between the ages of 1 and 2, which translates to one additional febrile seizure per every 2,300 to 2,600 MMRV doses administered in this age group.

Related: Measles has long-term health consequences for kids. Vaccines can prevent all of them.

"We — and by 'we,' I mean pediatricians and vaccine experts and the ACIP — were appropriately concerned about this, and there was incredibly thoughtful deliberation about how recommendations should change," said Dr. David Higgins, an assistant professor of pediatrics at the University of Colorado Anschutz Medical Campus. The committee determined that it's preferred that children under 4 get the MMR and chickenpox vaccine as separate shots.

However, because the risk of febrile seizures tied to the vaccine is small, the committee left open the option for parents who wanted one less needle for their kids to opt for the MMRV after being informed of the risks and benefits.

In general, between 2% to 5% of children under 5 sometimes experience seizures in response to a fever (caused either by an infection or a vaccination), and about one-third of kids who have one febrile seizure will go on to experience more. While kids with a history of febrile seizures have a slightly higher chance of developing epilepsy later in life, in almost all cases, the fever-induced seizures cause no damage and go away as the child ages.

If the ACIP restricts patients' option to get the MMRV vaccine, clinics that use the shot will likely see supply problems, Higgins told Live Science.

Both the MMRV and MMR vaccines prevent measles, which can cause deadly pneumonia, brain swelling, immune memory loss, and sometimes a progressive and fatal neurological disorder called subacute sclerosing panencephalitis (SSPE). They also prevent mumps, a viral infection that can cause deafness and male infertility; and rubella, a viral infection that causes a fever and rash and that, in pregnant women, can result in abnormal heart and brain development for the fetus.

The chickenpox vaccine not only prevents the painfully itchy viral infection, but also reduces the risk of kids getting shingles, a blistering rash caused by the same virus that causes chickenpox reactivating in the nervous system long after the initial infection passes.

Creating a controversy

A 2017 policy statement from the American Academy of Pediatrics summarizes the safety data on the hepatitis B vaccine in Vaccine Safety Datalink, a huge vaccine-safety monitoring project started in 1990. Per those data, there is "no evidence of a causal association between receipt of hepatitis B vaccine and neonatal sepsis or death, rheumatoid arthritis, Bell’s palsy, autoimmune thyroid disease, hemolytic anemia in children, anaphylaxis, optic neuritis, Guillain-Barré syndrome, sudden-onset sensorineural hearing loss, or other chronic illnesses."

There's no sign of any new data that would change this conclusion. But bringing it up at the ACIP meeting will likely feed a lack of trust in vaccination, overall, Barron said.

"All of this is external noise to cause skepticism and to cause alarm around vaccines in general," Barron said. "This multifaceted attack against vaccines that have existed for 30 to 40 years, have been used safely and effectively during that time, without new studies, without new data — I really feel it's just another tactic to scare people."

The meeting may also be an opportunity to spread fears about the timing of the childhood vaccine schedule in general — a frequent point of attack by anti-vaccine advocates. While activists claim the safety of the schedule has not been studied, that's untrue.

"At each stage, it has been studied to see whether the new vaccine added to the schedule will cause noteworthy adverse effects," Schaffner said. "That's before the recommendation is made."

After the addition of a new vaccine to the schedule is made, there are multiple safety reporting systems in place to monitor for any side effects not caught in trials — like the one that caught the increased risk of febrile seizures in young kids with the MMRV vaccine. These systems enable long-term studies that look for any serious outcomes over time across the population, Higgins said. And "we have not seen any credible connections there."

America's Health Insurance Plans (AHIP), a trade group of private insurers, announced in a statement on Sept. 16 that insurers would continue to cover vaccines that were recommended as of Sept. 1, 2025, until at least the end of 2026. But half of U.S. kids get their vaccines through the federal Vaccines for Children program, and ACIP recommendations directly determine which vaccines are included in that program.

The program specifically serves uninsured and underinsured children; kids who are on or eligible for Medicaid; and American Indian or Alaska Native children who qualify under the Indian Health Care Improvement Act.

"While I love seeing the health insurers come out and say, 'We think vaccines are important; we are going to cover them,'" Higgins said, "I am really worried about the half of children in the U.S. who get vaccines through the Vaccines for Children Program."