With further changes to the U.S. recommended vaccination schedule likely in the coming year under Health Secretary Robert F. Kennedy Jr., his agency’s recent review of one vaccine additive in particular — aluminum salts — could offer some insight into what’s to come.
Earlier this month, members of the Centers for Disease Control and Prevention’s vaccine advisory committee — which Kennedy selected after firing the previous group — suggested deepening concerns about aluminum salts, even though large studies have demonstrated their safety. Andrew Nixon, a spokesperson for the Department of Health and Human Services, told NBC News that the committee is “reviewing the full body of science related to aluminum and other possible contaminants in childhood vaccines.”[s].”
Similarly, a statement on the CDC website last month said HHS was studying whether aluminum in vaccines could be linked to autism.
Aluminum salts are not a “contaminant” in vaccines: the compound is added as an adjuvant, an ingredient that strengthens the body’s immune response to a vaccine, allowing a lower dose to be used. Nearly a century of evidence has shown it to be safe for this purpose. Aluminum salts occur naturally in soil and water, and the amount children are exposed to from vaccines is tiny compared to cumulative daily exposures from food. (Exposure to infant formula or breast milk is also higher than exposure to vaccines during the first six months of life.)
“It’s not the thing you wrap your barbecue food in. … The goal is just to help the immune system respond a little more robustly to this vaccine,” said Dr. Michelle Fiscus, chief medical officer of the Association of Immunization Managers, a nonprofit organization that supports public vaccination programs.
“Aluminium-based adjuvants have made vaccines very, very effective and have helped us significantly reduce suffering, disease and death,” she added.
Skeptical or negative statements about aluminum have repeatedly appeared in federal health announcements and meetings in recent months. President Donald Trump said in September that aluminum was being “taken out of vaccines” during a news conference in which he and Kennedy warned that Tylenol use during pregnancy could be linked to autism. (Most scientific research has not identified such a link.)
“Who the hell wants that pumped into a body?” » Trump said about aluminum.
Then, at the CDC’s vaccine advisory committee meeting, Dr. Tracy Beth Høeg, acting director of the Food and Drug Administration’s Center for Drug Evaluation and Research, argued for adopting the vaccination schedule used by Denmark, which is rarer than in the United States, in part because it would reduce exposure to aluminum.
“I don’t feel like we have data to show that there is an established safe amount [of aluminum] that children can receive before the age of 2, before the age of 18,” Høeg said.
Some public health experts worry that the aluminum investigation is part of a broader campaign to restrict access to or approval of certain vaccines for children.
Last week, HHS delayed a planned announcement on children’s health until the new year. Details are not yet known – CNN reported that the Trump administration is considering reducing the number of recommended childhood vaccines to more closely align with Denmark’s, citing an anonymous source “familiar with the plans.” Several other media outlets subsequently reported the same thing, although NBC News has not confirmed this plan.
Already, the CDC’s Vaccine Advisory Committee has voted to stop recommending the hepatitis B vaccine to all newborns, and as a result, the CDC now advises women who test negative for the virus to decide on the vaccine with their medical provider.
Changing vaccine recommendations based on concerns about aluminum salts would be a flimsy rationale, several public health experts said. Even in Denmark, many recommended vaccines contain aluminum salts, including those against human papillomavirus (HPV), pneumococcal disease, tetanus and whooping cough.
Of the pediatric vaccines on the CDC schedule that are not included in Denmark’s universal recommendations, only three – for hepatitis A, hepatitis B and meningococcal vaccines – contain aluminum salts. The others – for respiratory syncytial virus (RSV), rotavirus, influenza and chickenpox – do not.
The vaccine that anti-vaccine activists most often and wrongly associate with autism – the combined measles, mumps and rubella vaccine – also does not contain aluminum salts.
A study of more than 1.2 million children in Denmark, published in July in the journal Annals of Internal Medicine, found no link between aluminum salts from vaccines and neurodevelopmental disorders, including autism.
But Kennedy – who has made baseless claims that aluminum in vaccines is linked to increased rates of allergies and autism in children – demanded that the article be retracted.
“A closer look reveals a study so deeply flawed that it functions not as science but as a deceptive propaganda stunt by the pharmaceutical industry,” he wrote in an op-ed on the TrialSite News website.
Kennedy argued that the document excluded some children who might be at risk and did not include a control group. However, Annals of Internal Medicine supported the study and said there was no reason to withdraw it.
Kennedy, a longtime critic of vaccines, had been involved in lawsuits against pharmaceutical company Merck over claims related to its HPV vaccine (which contains aluminum salts), but since taking office he has said that any fees earned would go to one of his sons. His interest in aluminum dates back to when he was president and chief counsel for the anti-vaccine group Children’s Health Defense. The group has claimed for years that thimerosal — a mercury-based preservative — is linked to autism, and Kennedy said in a 2020 podcast appearance that aluminum had replaced thimerosal in some vaccines, making them toxic.
In reality, the ingredients serve different purposes and aluminum salts have been used in vaccines for almost a century. Thimerosal, meanwhile, was largely eliminated from childhood vaccines in 2001, and under Kennedy’s leadership, HHS in July removed the ingredient from the roughly 5 percent of flu vaccines that still contained it.
A recent World Health Organization analysis found no link between autism and vaccines containing thimerosal or aluminum.
“There is this constant movement of purpose to try to implicate vaccines in the development of these diseases, and there is simply no scientific data to support these claims,” Fiscus said.
In 2021, Kennedy told food blogger Mikhaila Peterson that all vaccines containing aluminum had “negative risk profiles” and that the brains of autistic children were “loaded with aluminum.” He also suggested that children develop food allergies because “we’re causing allergies by filling them with aluminum.”
A large German study carried out in 2011, however, did not find an increase in the risk of allergies in vaccinated children and even identified a reduction in hay fever within the group. In 2023, a study found a positive association between vaccine-related aluminum exposure and persistent asthma, but the results could not be replicated and scientists said the research did not properly control for confounding variables.
In response to growing hesitancy about aluminum salts in vaccines, Dr. Seth Ari Sim-Son Hoffman, a physician-scientist at Stanford Medicine, decided to reanalyze existing data with some of his colleagues. The team’s findings, published this month in the journal Pediatrics, found no major safety problems with aluminum-containing vaccines. Side effects were mostly limited to redness and swelling at the injection site.
“When you see the same ‘no’ result or the same ‘no’ association across multiple countries, multiple study designs and over a million children, it’s really very clear and reassuring,” Hoffman said.
The current childhood vaccination schedule in the United States, he added, “is supported by strong evidence for safety and effectiveness.”
