Health
Kennedy’s Vaccine Committee Endorses Preservative-Free Fall Flu Shots. Here’s What to Know
Lyn Redwood, a nurse practitioner who once ran the anti-vaccine group that Robert F. Kennedy Jr. founded, attends a meeting of the Advisory Committee on Immunization Practices at the Centers for Disease Control and Prevention in Atlanta on Thursday, June 26, 2025. (AP Photo / Shelby Lum)
ATLANTA (AP) — The Trump administration’s new vaccine advisers on Thursday endorsed this fall’s flu vaccinations for just about every American but threw in a twist: Only use certain shots free of an ingredient antivaccine groups have falsely tied to autism.
What is normally a routine step in preparing for the upcoming flu season drew intense scrutiny after U.S. Health Secretary Robert F. Kennedy Jr. abruptly fired the influential 17-member Advisory Committee on Immunization Practices and handpicked replacements that include several vaccine skeptics.
That seven-member panel bucked another norm Thursday: It deliberated the safety of a preservative used in less than 5% of U.S. flu vaccinations based on a presentation from an antivaccine group’s former leader — without allowing the usual public presentation of scientific data from the Centers for Disease Control and Prevention.
The preservative, thimerosal, has long been used in certain vaccines that come in multi-dose vials, to prevent contamination as each dose is withdrawn. But it has been controversial because it contains a small amount of a particular form of mercury.
Study after study has found no evidence that it causes autism or other harm. Yet since 2001, vaccines used for U.S. children age 6 years or younger have come in thimerosal-free formulas — including single-dose flu shots that account for the vast majority of influenza vaccinations.
The panel voted 5-1, with one abstention, that people ages 6 months and older get a flu vaccination this fall only using single-dose formulas that are thimerosal-free.
“There is still no demonstrable evidence of harm,” one adviser, Dr. Joseph Hibbeln, a psychiatrist formerly with the National Institutes of Health, said in acknowledging the panel wasn’t following its usual practice of acting on evidence.
But he added that “whether the actual molecule is a risk or not, we have to respect the fear of mercury” that might dissuade some people from getting vaccinated.
The ACIP, created more than 60 years ago, helps the CDC determine who should be vaccinated against a long list of diseases, and when. Those recommendations have a big impact on whether insurance covers vaccinations and where they’re available.
Kennedy has long held there was a tie between thimerosal and autism, and also accused the government of hiding the danger. Thimerosal was placed on the meeting agenda shortly after Kennedy’s new vaccine advisory was named last week.
Some public health experts contend the thimerosal discussion unnecessarily raised doubt in vaccines while possibly also making them more expensive and harder to get this fall.
At the panel’s meeting Wednesday, Chrissie Juliano, executive director of the Big Cities Health Coalition, lamented the ouster of the former ACIP panel and the agenda of the new one.
Her organization, which represents large city health departments, “is deeply concerned that many routine vaccines may soon become inaccessible or unaffordable for millions of Americans if ACIP makes changes based on ideology rather than science,“ she said. ”The stakes are simply too high to let that happen.”
What is thimerosal?
Thimerosal is a preservative used in certain vaccines since the 1930s, as well as in some other medical products.
It was mostly used in multi-dose vials of vaccine, to prevent bacterial contamination as the vessel was repeatedly punctured to withdraw a dose.
Why is thimerosal controversial?
Questions about thimerosal were raised in the late 1990s because it contains a form of mercury.
It’s not the same as the toxic type found in some seafood, called methylmercury. Instead, it’s a different type called ethylmercury that the body can excrete, said Dr. Sean O’Leary of the American Academy of Pediatrics.
The amount of ethylmercury per vaccine dose was small and studies found no evidence of harm. Nor was it used in all vaccines. For example, vaccines for chickenpox, polio and measles, mumps and rubella never contained it, according to the Centers for Disease Control and Prevention.
But as a precaution, the U.S. phased the preservative out of childhood vaccines. Since 2001, all vaccines routinely recommended for children age 6 and younger in the U.S. come in formulas that don’t contain thimerosal.
The exception is a small subset of flu shot formulas in multi-dose vials that could be used for adults or kids. The vast majority of children, however, get their flu vaccination from a single-dose shot instead, O’Leary said.
According to the CDC, 96% of all flu vaccines in the U.S. administered last fall and winter — and an even higher share of those used in federally funded programs — were thimerosal-free.
