Robert F. Kennedy Jr. often trained his criticism of vaccines on a common ingredient: Aluminum is responsible for childhood illnesses such as food allergies, autism, and depression.
“You wonder why a generation of kids are allergic to things,” Kennedy said in a 2021 interview. “That's because we induce allergies and we're full of aluminum.”
Aluminum is an odd target for many vaccine scientists. It is one of the most studied ingredients in vaccines, and perhaps modern medicine.
“There is a tremendous amount of information that has been collected,” said Dr. Andrew Racine, pediatrician and chief medical officer at Montefiore Health System. “If there was something that jumped out about a lack of safety, we would think we saw it somewhere, and it just doesn't show up.”
Aluminum salts, a more soluble metal, are added to vaccines like the TDAP shot to boost the body's immune response. The ingredients have been repeatedly evaluated as part of vaccines in clinical trials and have been administered in billions of doses over decades.
Still, as Mr. Kennedy prepares for his confirmation hearing as secretary of the Department of Health and Human Services, many experts fear that the standby will face new scrutiny, similar to the hepatitis B shot. It may even serve as a justification for restricting access to some pediatric vaccines and pneumococcal disease.
Aaron Siri, a lawyer and close ally of Mr. Kennedy, petitions federal regulators to suspend distribution of more than a dozen vaccines until manufacturers provide more information about the amount of aluminum in their formulations. represents clients who
Kennedy and Siri did not respond to requests for comment.
The origins of aluminum added in vaccines can be traced back nearly a century. In a stable on the outskirts of Paris, a young veterinarian made a unique discovery. Tapioca was mixed into equine diphtheria vaccines to make them more effective.
Physician Gaston Ramon noticed that horses that developed a mild infection at the injection site had a much more robust immunity to diphtheria. He theorized that adding something to the shot that caused inflammation – an ingredient he later derived from the Latin root “help” – would help induce a stronger immune response.
After testing several candidates, including bread crumbs, petroleum jelly, and rubber latex, he had success with an injection of tapioca layers, which produced slight swelling and much more antibodies.
Tapioca was never caught as an adjuvant. However, in 1932, a few years after Dr. Ramon's research was published, the United States began including aluminum salts in diphtheria vaccinations.
Today, aluminum adjuvants are found in 27 routine vaccines, nearly half of which are recommended for children under 5 years of age.
Vaccines of any kind do not require this extra boost of immunity. Shots that contain weakened forms of the virus, such as the measles mumps and rubella shots, or those made with mRNA technology, such as the Pfizer and modern Covid-19 vaccines, generate sufficient immune responses on their own.
However, for vaccines that contain only small fragments of the pathogen, adjuvants can stimulate a stronger response and require fewer doses of the vaccine to receive little attention from the immune system.
Scientists believe that aluminum salts work in two ways. First, aluminum binds to the vaccine's core ingredient and diffuses it into the bloodstream more slowly, giving immune cells more time to build a response.
Aluminum is also thought to act more directly, increasing the activity of certain immune cells, although the mechanism is not fully understood.
Aluminum salts are not the only adjuvants on the market, but vaccine manufacturers often prefer them because of their long track record of safety data.
Each new vaccine that uses aluminum adjuvants undergoes lengthy clinical trials to assess its safety, and side effects are continuously monitored after approval. One of the earliest tests involving an aluminum adjuvant was published in 1934.
Later trials revealed some minor side effects, including redness, body aches, and in rare cases, painful nodules at the injection site. However, as Kennedy suggested, there is little reliable evidence that aluminum in vaccines causes serious long-term side effects.
People who are routinely exposed to large amounts of aluminum, such as workers who breathe aluminum dust or dialysis patients who routinely receive aluminum-rich medications, may experience respiratory, bone, and neurological complications. There is.
But the amount of aluminum in pediatric vaccines is trivial compared to what people are routinely exposed to through the environment and food, said Dr. Michael Moody, director of the Duke Human Vaccine Institute. Ta.
“We are constantly exposed to aluminum,” he said. “When you inhale dust from outside, it’s coming into contact with the aluminum.”
In the first six months of a baby's life, the vaccine exposes them to about 4.4 milligrams of aluminum. In contrast, one slice of American cheese can contain 50 milligrams of aluminum.
Scientists found no significant differences in aluminum levels in the blood and hair of babies who received vaccines containing aluminum compared to those who did not.
Some scientists believe one potential side effect requires additional research.
In 2022, after a federally funded study found a modest association between aluminum exposure from vaccines and asthma, the CDC noted that the link warranted “further investigation.” (The agency said it does not change vaccine recommendations “based on a single study.”)
Kennedy, then president of Children's Health Defense, a nonprofit organization frequently critical of vaccines, held up the study as evidence that vaccinations were causing an “asthma epidemic.”
However, the paper's authors were careful to point out the limitations of their findings. Most notably, the effect is small, meaning the study is observational. In other words, cause and effect cannot be proven.
The paper warned that their results “do not constitute strong evidence to question the safety of aluminum in vaccines.”
The independent experts also said the authors did not collect data on some important risk factors, such as whether participants had been exposed to tobacco smoke or had a family history of asthma.
In response to this study, a group of researchers from Statens Serum Institut, a Danish public health agency, conducted a similar analysis on a national dataset of more than 450,000 children.
Their preliminary results did not show an association between aluminum adjuvants and asthma, they told the CDC's Advisory Committee on Immunization Practices in 2023.
Still, a CDC spokesperson said the agency is “discussing additional studies” to investigate potential risks.
But until rigorous studies confirm the findings, the link between aluminum and asthma is tenuous at best, said Dr. Stanley Plotkin, who played a pivotal role in helping create the rubella vaccine. .
“You can't change the conclusions from a single paper,” he said. “You have to look at the overall literature.”
Anders HVIID, who led the Danish study, said he welcomed more research into the safety of the adjuvant, but said these studies would not convince skeptics that aluminum does not cause long-term side effects. It may not be enough, he added.
“You can’t prove a negative,” he said. “There’s always this goalpost movement.
