With a lack of data and confusing language, the panel tabled the vote indefinitely.
Catherine Stein, far right, speaks during a meeting of the CDC's Advisory Committee on Immunization Practices on September 18, 2025 in Chamblee, Georgia. Credit: Getty | Elijah Nouvelage
The second day of a two-day meeting of the Advisory Committee on Immunization Practices—a panel currently made up of federal vaccine advisors hand-selected by anti-vaccine activist Robert F. Kennedy, Jr.—is off to a dramatic start, with the advisors seemingly realizing they have no idea what they're doing.
The inexperienced, questionably qualified group that has espoused anti-vaccine rhetoric started its second day of deliberations by reversing a vote taken the previous day on federal coverage for the measles, mumps, rubella, and varicella (MMRV) vaccine. Yesterday, the group voted to restrict access to MMRV, stripping recommendations for its use in children under age 4. While that decision was based on no new data, it passed with majority support of 8–3 (with one abstention). (For an explanation of that, see our coverage of yesterday's part of the meeting here.)
But puzzlingly, they then voted to uphold access and coverage of MMRV vaccines for children under age 4 if they receive free vaccines through the federal Vaccines for Children program, which covers about half of American children, mostly low-income. The discrepancy projected the idea that the alleged safety concerns that led the panel to rescind the recommendation for MMRV generally, somehow did not apply to low-income, vulnerable children. The vote also created significant confusion for VFC coverage, which typically aligns with recommendations made by the panel.
Today, Kennedy's ACIP retook the vote, deciding 9-0 (with three abstentions) to align VFC coverage with their vote yesterday to strip the recommendation for MMRV in young children.
Hepatitis B vaccine newborn dose
Next, they moved to a vote they failed to take yesterday as scheduled—a vote to strip a recommendation for a dose of hepatitis B vaccine that is currently recommended to be given universally on the first day of a baby's life. Instead, the proposed recommendation would be to wait at least a month before the first dose—opening a window for a highly infectious disease that leads to chronic liver disease and cancer—unless the baby's mother tested positive for the virus.
While it initially seemed that the panel was poised to approve the change, cracks in the plan began to appear quickly this morning, as some members of the panel noted that the proposed recommendation made no sense and was based on zero data.
Joseph Hibbeln, a psychiatrist on the panel, raised the obvious concern yesterday, saying: "I'm unclear if we've been presented with any safety or data comparing before one month to after one month, and I'm wondering why one month was selected as our time point and if there are data to help to inform us if there's greater risk of adverse effects before one month or after one month at all, let alone in negative mothers."
There was no data comparing the risks and benefits of moving the first dose from the day of birth to any other time point. And there is no data suggesting that such a move would be more or less safe.
Adam Langer, Acting Principal Deputy Director of the CDC's National Center for HIV, Viral Hepatitis, STD, and Tuberculosis Prevention, stressed in his presentation on the safety data yesterday, that the vaccine is safe—there are no safety concerns for giving a dose at birth. Adverse side effects are rare, he said, and when they do occur, they're mild. "The worst adverse event you could imagine, anaphylaxis, has been very rarely reported at only 1.1 cases per 1 million vaccine doses administered."
Langer gave a clear explanation for why newborns are vaccinated at day one. Hepatitis B, which primarily affects the liver, spreads via bodily fluids and can live on surfaces for up to seven days. It can spread easily; only a tiny microscopic amount of blood or fluid is enough for a child to be infected. For some, an infection can be short-lived, but for others it can become chronic, which leads to liver disease, cirrhosis, liver transplant, and liver cancer. The risk of the infection becoming chronic increases with the younger someone is when they're infected.
Benefits and harms
Newborns who get hepatitis B from their mothers at birth have a 90 percent chance of developing a chronic infection, and 25 percent of those children will die prematurely from the disease. Up to 16 percent of pregnant women in the US are not tested for hepatitis B during pregnancy. Newborns and babies can also get infected from other people in their family or household, given hepatitis B's infectiousness. Prior to the universal birth dose recommendation, a study of US-born children born to immigrant mothers found that 7 percent to 11 percent of them had hepatitis B while their mothers were negative. This highlights that unvaccinated babies and children can pick up the infection from family or the community.
Part of the reason for this is the elusiveness of the disease. While about 2.4 million people in the US are infected with hepatitis B, about 50 percent of those infected do not know that they're infected.
In 1991, ACIP began recommending universal hepatitis B vaccination at birth; acute hepatitis B cases then fell from around 18,000 to about 5,500 in 2005 to about 2,200 in 2023. Since 2018, ACIP has recommended universal Hep B vaccination for all newborns within 24 hours of birth.
In the discussion, panel members pushed back on the universal birth dose, arguing that if mothers tested negative, there was little to no risk—downplaying the risk of other family or community exposure and assuming that test coverage could increase to 100 percent. There was a lot of discussion of why some women aren't tested and if doctors can just try to assess whether there's a risk that a family member might have the infection—even if those family members don't know themselves that they're infected.
Data and trust
Langer acknowledged there might be ways to assess risk from at least the mother in the 24-hour window after birth—"or," he suggested, "you cannot have to worry about all of those different things that could go wrong, and you could simply give the vaccine because there is no data available that says that there is any harm that would come to a newborn compared to a one-month-old infant [getting the vaccine.]"
He summed up the discussion succinctly: "The only thing that we're discussing here is if there's some benefit or removal of harm that comes from waiting a month. And I have not seen any data that says that there is any benefit to the infant of waiting a month, but there are a number of potential harms to the infant of waiting a month."
Panel member Robert Malone, who has falsely claimed that COVID-19 vaccines cause a form of AIDS, explained that the proposed change for the hep B vaccination was not due to any safety concern or evidence-based reason, but about trust among parents who have been exposed to vaccine misinformation.
"The signal that is prompting this is not one of safety, it is one of trust," Malone said yesterday. "It is one of parents uncomfortable with this medical procedure being performed at birth in a rather unilateral fashion without significant informed consent at a time in particular when there has been a loss of trust in the public health enterprise and vaccines in general."
Dashed decisions
But the questions and uncertainties of the proposed recommendation and the data behind it dogged the committee again this morning.
This morning, the voting language was put on a slide and immediately drew criticism. The language was:
If a mother tests [hepatitis B]-negative:
- The first dose of the Hepatitis B vaccine is not given until the child is at least one month old.
- Infants may receive a dose of Hepatitis B vaccine before one month according to individual based decision-making. *
*Also referred to as shared clinical decision-making.
Hibbeln, the psychiatrist, again pushed back, this time noting that the language of the change is confusing. "You can't say don't give it and then give an opportunity to give it," he said, arguing that shared clinical decision-making is, essentially, all or nothing.
Discussion quickly spiraled, with another member questioning whether there was any data presented at all on the proposed recommendation. There was a fast motion to table the vote indefinitely, and the motion to table passed in a speedy vote of 11–1, with the ACIP chair, Martin Kulldorff, being the only holdout.
For the rest of the day, the panel is discussing COVID-19 vaccines. Stay tuned.
Beth is Ars Technica’s Senior Health Reporter. Beth has a Ph.D. in microbiology from the University of North Carolina at Chapel Hill and attended the Science Communication program at the University of California, Santa Cruz. She specializes in covering infectious diseases, public health, and microbes.