Here’s What Happened at RFK, Jr.’s Overhauled Vaccine Panel Meeting
Three vaccines were on the agenda for this week’s meeting of ACIP, the CDC’s key advisory panel on immunization: the combined measles, mumps, rubella and varicella vaccine, the hepatitis B vaccine and COVID vaccines
This week’s meeting of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices represented a notable departure from its prior practice of presenting and debating high-quality data on vaccine safety and risk-benefit analyses. Committee members, many of whom were hastily installed by Secretary of Health and Human Services Robert F. Kennedy, Jr., cited—without solid evidence—hypothetical risks of immunization with mRNA COVID vaccines, disregarding extensive studies showing the Food and Drug Administration–approved vaccines are safe and effective. The consequences of this meeting extend far beyond the specific votes the committee made today and could undermine confidence in vaccines and the U.S. medical establishment more broadly, some experts have noted. The story below has been updated with details of the discussion and votes regarding each vaccine considered.
The already tumultuous landscape of U.S. vaccine policy faces more turmoil in what’s anticipated to be a politically charged two-day meeting of a recently overhauled advisory panel to the Centers for Disease Control and Prevention.
The Advisory Committee on Immunization Practices (ACIP) is an independent panel of experts that has traditionally met three times a year to make science-based recommendations about who should receive certain vaccines. But this year the Trump administration’s efforts to undermine science and public health has upended the committee. Just yesterday former CDC director Susan Monarez, who led the agency for a month, testified to the Senate about her experience of being pushed out of office for not condoning attacks on vaccines unsupported by evidence. Most dramatically, Robert F. Kennedy, Jr., secretary of health and human services and a veteran antivaccine activist, fired the panel’s membership, with the newest appointees announced only days ago.
On September 18 and 19, the committee is holding its second meeting of the year, and experts now worry that the new ACIP members will continue eroding public access to lifesaving vaccinations. Already, one in six parents in the U.S. reports delaying or skipping a vaccine for their child, according to a recent poll.
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“I fear for the health of children in this country,” says Paul Offit, a pediatric infectious diseases specialist at Children’s Hospital of Philadelphia. “RFK, Jr.’s goal is to make vaccines less available, less affordable and more feared. That’s his goal, and he’s doing a great job of it.”
ACIP’s decisions are important because they dictate the price of lifesaving preventive care. The Affordable Care Act requires private insurance companies to cover ACIP-recommended vaccines at no cost; government-run insurance programs, including the Vaccines for Children (VFC) program, which covers half of childhood vaccines administered nationwide, also base costs on the panel’s decisions.
At this week’s meeting, the newly reconstituted panel will discuss three vaccines: the combined measles, mumps, rubella and varicella vaccine, the hepatitis B vaccine and this year’s updated COVID shots.
The meeting’s agenda is a departure from ACIP’s norm, says Edwin Asturias, a pediatric infectious disease specialist and epidemiologist at the University of Colorado, who joined ACIP in July 2024 and was dismissed during Kennedy’s overhaul of the committee earlier this year. “This is one of the shortest agendas that we have seen for a long time from ACIP,” Asturias says. “Typically, ACIP has a lot of things to look through because there’s a lot of vaccines that are advancing through different aspects of development, as well as new data being generated.” Meetings in 2024 each discussed at least eight different vaccines.
READ MORE: See Vaccine Recommendations Backed by Science in These Handy Charts
Asturias and other public health experts are particularly worried the meeting will institutionalize attacks on the childhood vaccine schedule—a carefully choreographed, evidence-based timeline of vaccines given to kids in their earliest years.
“The childhood immunization schedule has proven to be very effective at reducing a lot of diseases that cause a lot of pain, suffering, and death in children,” Asturias says.
The meeting will be livestreamed on both September 18 and September 19. Here’s what experts are keeping an eye on.
This story will be updated throughout the meeting.
What Happened
Members voted 8-3 not to recommend the single combination MMRV vaccine before age four, removing the option for children younger than four years old to receive the shot for the first dose. Children younger than age four are recommended separate MMR and varicella vaccines.
This decision came after long deliberation over concerns about the occurrence of a common type of seizure after the combined vaccination in younger age groups (see more below). Previously, children as old as 12 months could get the single MMRV shot as their first dose. But the preferred approach has been to administer separate MMR and varicella vaccines at 12 to 15 months old and then to give an additional combined shot at four to six years old to reduce the cumulative number of vaccines and visits required.
On September 18 the committee also voted to approve continued coverage of the combined vaccine under the VFC program. But upon reconvening the meeting on September 19, ACIP chair Martin Kulldorff said that at least one committee member had privately expressed confusion about what precisely the committee had been voting on. Kulldorff then led a new vote, which determined, by 9-3, not to recommend VFC coverage for the combined MMRV shot for those younger than age four.
About the Vaccine
This vaccine offers protection against four diseases—measles, mumps, rubella and chicken pox, or varicella—in a single shot. It’s distinct from the measles, mumps and rubella (MMR) vaccine and was authorized in the U.S. for use in children between one and 12 years old in 2005, about a decade after the introduction of an independent vaccine that only protects against varicella zoster, the virus that causes chicken pox.
About the Diseases
Measles is one of the most contagious viruses known to science; doctors have no cure for the infection and can only treat its symptoms. Most people who catch measles develop a high fever and a characteristic rash, but extreme cases can cause inflammation in the brain—and in a small number of cases, usually in children, the virus lingers dormant in the nervous system for years before causing fatal inflammation. Mumps is a viral infection characterized by the swelling of certain salivary glands and can also trigger miscarriage early in pregnancy. Rubella, sometimes called German measles, is unrelated to measles but is also characterized by a rash. When contracted early in pregnancy, the infection causes serious birth defects in about 90 percent of cases. The varicella-zoster virus causes not just the itchy chickenpox rash but sometimes systemic infections, pneumonia and brain swelling. In addition, the virus can decades later trigger a painful rash called shingles.
What Experts Say
The ACIP agenda had noted a two-hour block to discuss the MMRV vaccine, including a presentation on febrile seizure, a type of convulsion, following the vaccine—a very rare complication, seen predominantly in children between 12 and 23 months old.
This known side effect is why doctors tend to give children their first dose of MMR and varicella protection as two separate injections, then switch to the combined vaccine for kids older than the window in which there is a slightly higher risk of febrile seizures. Speaking to Scientific American before the vote, Asturias worried that ACIP would decide to remove the combination vaccine option for parents looking to reduce the number of vaccines their children receive, in turn potentially reducing protection against these four infections. Such a change would “likely make it more complicated for families,” he said.
He was also particularly worried that removing the MMRV vaccine would mean children would miss out on the second dose of protection against measles—proven essential in effectively lowering cases. When the U.S. required only one dose of measles vaccination in the late 20th century, case rates remained high. It was only when the CDC began requiring a second dose that numbers fell. “We know that that second shot is very important,” Asturias said.
What Happened
Members voted to affirm that “all pregnant women should be tested for hepatitis B infection,” as is the current standard of care. Members considered an additional recommendation to remove the birth dose of hepatitis B vaccine for infants born of people who test negative for the virus while pregnant, with the first dose not given earlier than one month of age. But the committee voted to table the measure indefinitely after a member raised concerns about the wording of the measure being contradictory: one bullet point removed the option of a birth dose for these infants while the other included the option of giving the first dose earlier than one month “according to individual based decision-making.”
About the Vaccine
The hepatitis B vaccine was first licensed for use in the U.S. in 1981 and recommended for people who were considered “high-risk,” such as health care workers and men who have sex with men. Despite the introduction of the vaccine, overall infection rates did not change for the next several years, however.
“Initially the strategy used by the CDC was trying to vaccinate high-risk groups,” Asturias says. “That strategy failed miserably.”
About the Disease
The hepatitis B virus can spread through blood, semen and other body fluids of an infected person and is capable of lasting up to seven days on surfaces. Additionally, it can be passed from parent to child during pregnancy, childbirth or through close contact with bodily fluids after birth.
The virus attacks the liver, and people don’t often show symptoms until years later, when they either develop hepatitis (liver inflammation), cirrhosis (severe liver disease) or liver cancer. In rare cases, people can die from this disease.
What Experts Say
Kennedy has repeatedly cast doubt on the vaccine’s safety. His newly appointed ACIP members have questioned the need for the birth dose—and former senior CDC officials have hinted that the panel may vote to recommend delaying until age four.
Current ACIP chair Kulldorff, who was handpicked by Kennedy, has questioned the timing of this vaccine. At the previous ACIP meeting in June, he said, “Unless the mother is hepatitis B positive, an argument could be made to delay the vaccine for this infection, which is primarily spread by sexual activity and intravenous drug use.”
Only 84 to 88 percent of pregnant women are screened for hepatitis B in the U.S., however, according to a 2019 report from the U.S. Preventative Services Task Force. Even if no one in the household is infected, infants could still be exposed, especially since more than 80 percent of people in the U.S. with hepatitis B do not know they have it, according to Mindie Nguyen, a hepatologist at Stanford Medicine, who spoke with Scientific American before the meeting.
“There’s no reason to wait” to vaccinate, she said. Infants who catch hepatitis B overwhelmingly become chronically infected, with no medical recourse. “Currently we have no cure for hepatitis B.”
Additionally, she worried a vote to delay the hepatitis B vaccine would make it more challenging for infants and children under four years old to access it.
“If you take away this birth dose of hepatitis B, which is there to prevent this infection early on, then we’ll see hepatitis B growing by the numbers over the years,” Asturias told Scientific American before the meeting. “But it may take us five to 10 years to see the impact of removing this birth dose.”
What Happened
The committee voted unanimously, 12-0, to recommend vaccination based on what’s known as individual-based decision-making, or shared clinical decision-making, for everyone older than the age of six months. That mechanism requires a conversation with a health care professional, which the members clarified can be a pharmacist, not solely a physician. The recommendation also noted that for people under the age of 65 years, “the risk-benefit of vaccination is most favorable for individuals who are at an increased risk for severe COVID-19 disease and lowest for individuals who are not at an increased risk.” Private and public insurers alike are required to fully cover vaccines recommended under shared clinical decision-making. Before the vote, Kulldorff confirmed that approving the measure would make the vaccine available at no cost for all individuals older than the age of six months.
After a heated discussion on whether to state that the committee felt that state and local jurisdictions should require a prescription for COVID vaccination, the committee voted 6-6 on the measure, with Kulldorff’s tie-breaking vote defeating it. The direct enactment of that proposal would likely go beyond ACIP’s authority, and the measure was phrased as expressing the “sense of the committee.” The measure failed largely because of concerns that it would leave pharmacists unable to provide vaccines, making them harder to access. The members also considered two other COVID-related items, which were also expressed as only “the sense of the committee”: here, they encouraged both the CDC and providers to provide additional details about risks and benefits of the vaccines.
About the Vaccines
This year, mRNA vaccines from Pfizer and Moderna and a protein-based vaccine from Novavax have been updated to protect against the most prevalent strains circulating in the U.S. It’s difficult to predict exactly how each year’s updated vaccine will perform against the strains that end up circulating, but last year’s vaccine reduced COVID-related urgent care and emergency room visit rates by about 33 percent among all adults compared with those who had not received an updated shot.
In recent years ACIP has voted to recommend updated COVID vaccines for everyone older than the age of six months. During this year’s June meeting, the panel discussed COVID vaccines but did not hold a vote on them. In August, however, the Food and Drug Administration authorized the vaccines only for people aged 65 years and older or with underlying health conditions that make them more vulnerable to severe infection.
About the Disease
COVID exploded onto the global scene as an entirely novel virus as 2019 turned to 2020. It has contributed to the deaths of more than 1.2 million people in the U.S. since its arrival. Even people who develop a mild infection are vulnerable to the lingering and sometimes debilitating constellation of symptoms dubbed long COVID.
What Experts Say
To many experts’ alarm, ACIP discussions were widely expected to drum up concern surrounding rare adverse incidents reported in children after vaccination, including unvetted reports of 25 childhood deaths. Vaccines, like all medical interventions, can come with side effects, but these are carefully monitored and evaluated during trials and after a vaccine is rolled out. Scientists continually reevaluate safety data to determine whether potential risks merit changing existing vaccines—for example, the U.S. stopped using an oral polio vaccine that used a weakened live virus in 2000 because it occasionally triggered polio infection.
And ever since COVID vaccines rolled out, people and health care providers have been able to report issues to a government program called the Vaccine Adverse Event Reporting System, or VAERS. Reports in this system, including of childhood deaths and birth defects, are prompting antivaccine activists to lobby for the removal or restriction of COVID vaccines. But this is driven by a misunderstanding of what adverse events mean, Offit told Scientific American before the meeting.
“The VAERS system does not allow one to determine whether a vaccine caused a problem,” he said. “The best you can say about VAERS is that it raises a hypothesis.” Investigators must dig into each individual report to determine whether the unfortunate incident was actually caused by a vaccine or simply a coincidence. Offit said he feared any misrepresentation would push people away from COVID vaccines, particularly for small children.
Such a move would be deeply concerning, Asturias said to Scientific American before the meeting, given that babies under one year old are just as likely to end up hospitalized from COVID as people between the ages of 65 and 75. “At six months, they have never seen COVID,” Asturias said. “There’s ample evidence that COVID in little babies, especially in their first year, if not the first two years, of life, is a disease that we should prevent.”
Editor’s Note (9/19/25): This article was edited after posting multiple times after posting on September 18 and September 19, 2025, to include updates about what happened during both days of the meeting.
Meghan Bartels is a science journalist based in New York City. She joined Scientific American in 2023 and is now a senior news reporter there. Previously, she spent more than four years as a writer and editor at Space.com, as well as nearly a year as a science reporter at Newsweek, where she focused on space and Earth science. Her writing has also appeared in Audubon, Nautilus, Astronomy and Smithsonian, among other publications. She attended Georgetown University and earned a master’s degree in journalism at New York University’s Science, Health and Environmental Reporting Program.
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