Posts Raise Unfounded Concerns About Aluminum in Vaccines

SciCheck Digest

Small amounts of aluminum have been used for many decades to strengthen the immune response to vaccines. Exposure to high levels of aluminum has been associated with brain and bone problems, but there is no evidence that the level of exposure provided by vaccines leads to such toxicity, contrary to social media claims.

What ingredients are in vaccines?

What ingredients are in vaccines?

All vaccines contain an active ingredient, or antigen, and tiny amounts of other substances that allow them to work, stay free of contamination and remain effective for longer. 

The antigen is a substance that prompts the body to mount an immune response, including protective antibodies. Antigens can be viruses, bacteria, parts of those or even the genetic code to produce parts of them. All viruses, bacteria or toxins used in vaccines are either inactivated or weakened so that they can’t make people sick. Manufacturers list the components of each vaccine on publicly available package inserts and anyone can check for possible allergens. 

Some vaccines may also contain adjuvants, preservatives, stabilizers and residual byproducts from the manufacturing process. All of these components are safe in the concentrations used in vaccines. Many of them are common and can be found in our bodies, drinking water, food or other products we ingest or use regularly. 

Adjuvants are substances that help vaccines work better by boosting the body’s immune response. Tiny amounts of aluminum salts, for example, have been safely used for this purpose for decades.

Preservatives are typically added to multidose vaccine vials to prevent contamination once a vial is opened. Although anti-vaccine groups falsely claim the tiny amounts of thimerosal, a preservative that contains ethylmercury, in vaccines is dangerous, it has been shown not to be harmful. Ethylmercury is not the same as methylmercury, a kind of mercury found in some fish and animals that can be toxic at high levels. Ethylmercury is safer because it’s broken down and excreted faster from the body. There is no link between thimerosal in vaccines and autism. Since 2001, thimerosal has not been used in any childhood vaccines in the U.S. other than multidose flu shots.

Stabilizers are used to keep the antigen stable during shipping and storage. These can include sugars, amino acids, proteins and gelatin.

Vaccines may also contain surfactants or emulsifiers used to keep all the ingredients blended together and prevent clumping. Anti-vaccine groups sometimes focus on an emulsifier called polysorbate 80 to spread fear. But the compound, which is safely used in vaccines, is found in much higher concentrations in many foods, including ice cream.

Trace amounts of other substances from the manufacturing process sometimes remain in vaccines. For example, many vaccines are made by growing viruses or producing proteins in chicken eggs or cell lines, so vaccines may contain DNA or proteins from those cells or other products from the growth media. Similarly, inactivated vaccines may contain formaldehyde, which is used to kill viruses. Again, the amounts of these substances in vaccines are minuscule and harmless, since the antigens are purified before being put into vials. No vaccine contains fetal cells or tissue.

No vaccines contain antifreeze, despite claims to the contrary. The confusion often stems from the fact that antifreeze contains ethylene glycol, and some vaccines contain polyethylene glycol. While the names are similar, the compounds are very different. The one in vaccines is nontoxic and found in a variety of skin products and medicines.

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Adjuvants in vaccines — ingredients added to increase efficacy — help spur the immune system to mount a strong response to the vaccines’ main ingredients. Aluminum serves as an adjuvant in some vaccines, such as those against diphtheria, tetanus and pertussis, and hepatitis A and B.

Aluminum is found in the Earth’s crust, water and the air, as well as in a variety of foods, drugs and other products. Animal and human studies indicate that high doses of aluminum can have neurological effects. People with impaired kidneys who are exposed to too much aluminum over time via dialysis or nutrition delivered directly into their bloodstream have developed problems with their brains and bones.

However, exposure to the small amounts of aluminum in vaccines poses an “extremely low risk to infants,” according to calculations by scientists from the Food and Drug Administration.

Nevertheless, social media posts regularly raise unfounded concerns about aluminum in vaccines, including that it can harm the nervous system, that it exceeds safe levels or it is unsafe because it never leaves the body. As we have written, this is part of a larger pattern in which people attempt to raise concerns about vaccines by making unfounded claims of harms from substances present in tiny amounts.

“Aluminum is a known neurotoxin,” said one recent post on Instagram. “If we keep bombarding the system over and over at so many well visits with an increasing scheduling there has to be a breaking point,” the post misleadingly said, referring to aluminum exposures from vaccines.

The post went on to refer to an FDA “safety limit” of 5 micrograms aluminum per kilogram body weight per day, juxtaposing it with amounts of aluminum in vaccines. But FDA draft guidance recommends this as the limit for total daily aluminum exposure via nutrition products infused intravenously, given to people who cannot absorb nutrients through their guts. This limit does not apply to vaccines, which have their own aluminum limits.

“There are conditions where aluminum can harm the nervous system,” Robert Yokel, an emeritus professor at the University of Kentucky who has studied the toxicology of aluminum, told FactCheck.org in an email. He referenced the example of dialysis patients who were exposed to high levels of aluminum infused directly into their blood.

However, “it is the dose (concentration) that is relevant,” Yokel said, adding that he is not aware of evidence that typical exposures to aluminum harm the brain.

Known Side Effects of Aluminum Adjuvants Are Typically Minor 

Aluminum adjuvants in vaccines can cause side effects at the injection site. These local reactions include “some redness, swelling, and a little bit of firmness,” Dr. Neal Halsey, director emeritus of the Institute for Vaccine Safety at Johns Hopkins University, told FactCheck.org, but these don’t lead to long-lasting problems.

Photo by Mathurin NAPOLY/matnapo via Unsplash.

Halsey said that in very rare cases, people can develop a hypersensitivity to the aluminum adjuvants after receiving multiple vaccine doses, leading to nodules at the injection site. This reaction occurs at an estimated rate of 300 to 8,300 per million people.

A recurrent misleading social media claim is that aluminum accumulates in the body and this means it’s unsafe. While most aluminum — whether from vaccines or other sources — is processed in the kidneys and excreted in urine, some does remain in the body. Of the aluminum that stays in the body, the majority is found in the bones.

“Over the human lifespan the aluminum concentration has been shown to increase in several organs, including the brain,” Yokel said.

However, he said, aluminum accumulation is not necessarily unsafe. “This is an example of the ‘dose making the poison,’” he said. “To conclude that aluminum accumulation results in an unsafe condition, without consideration of the level of accumulation, is a non-sequitur fallacy.”

To get a better sense of the possible impact of aluminum from vaccines on infants, researchers from the FDA in 2011 published an updated analysis of the amounts of aluminum infants would be exposed to via vaccine and dietary sources, including breast milk, formula and food.

As their benchmark, the researchers used a minimal risk level for aluminum established by the Agency for Toxic Substances and Disease Registry based on experiments in which mice were fed an aluminum salt. The studies measured neurological impacts on mice exposed to aluminum in utero and during early life. The minimal risk level is an estimate of how much of a substance a person can consume “without a detectable risk to health,” according to the agency.

Aluminum-containing vaccines are generally injected into the muscle, and the aluminum is released gradually into the bloodstream from the injection site over time. Taking into account the multiple possible sources of aluminum in the babies’ blood and the slow release from the vaccines, the body burden of aluminum would not be expected to rise above the safe limit, the researchers found. In fact, the level stayed at less than half the safe limit, they wrote, pointing out that this limit itself has a cushion built in and that exposure at or slightly above the limit might be safe.

“We conclude that episodic exposures to vaccines that contain aluminum adjuvant continue to be extremely low risk to infants and that the benefits of using vaccines containing aluminum adjuvant outweigh any theoretical concerns,” the FDA researchers wrote.

The researchers found that during infancy, the aluminum from vaccines at most might contribute twice the amount that the body absorbs from dietary sources, taking into account that the vast majority of aluminum in food or drinks is never absorbed into the body. Other research has indicated that overall, vaccines contribute a negligible amount of aluminum to children’s total exposure.

One study, published in 2017 in Academic Pediatrics, took blood and hair samples from 85 healthy children between 9 and 13 months of age. The researchers did not find a correlation between the vaccines the children had received and the amount of aluminum in their hair or blood, either when looking at total vaccine history or the vaccines they’d gotten the day of testing. This is in keeping with results of a smaller study of 2-month-old preterm infants, which also didn’t find a relationship between vaccination and blood aluminum levels.

Posts Misrepresent Aluminum Safety Limits

As we’ve discussed, there are FDA limits on the amount of aluminum that can be in individual vaccines. Despite this, social media posts repeat claims that aluminum in vaccines exceeds safe limits.

“If the baby’s typical size, and let’s say he or she weighs about 8 pounds, the amount of aluminum in the hepatitis B vaccine alone is almost 14 times the amount of aluminum that’s FDA approved,” Ty Bollinger misleadingly said in a video clip shared in a recent Instagram post. Bollinger, who owns a publishing company, has long been a prolific spreader of misinformation on topics such as cancer and vaccines.

The video refers to a limit of 5 micrograms of aluminum per kilogram body weight. But as we’ve said, this draft recommendation applies to total daily exposure from intravenous nutrition products. FDA regulations have also long stated that these intravenous nutrition products must carry a warning label stating that people with impaired kidney function, including premature babies, “accumulate aluminum at levels associated with central nervous system and bone toxicity” when exposed to levels greater than 4 to 5 micrograms per kilogram per day.

This recommended daily limit does not apply to vaccines, however. No available vaccines in the U.S. are given intravenously. Vaccines using aluminum adjuvants are generally injected in the muscle.

With intravenous nutrition, “100% is delivered into the blood immediately, from which it can distribute throughout the body and be eliminated (by the kidneys, which account for >95% of aluminum elimination),” Yokel explained.

By contrast, absorption of aluminum from vaccines “is not immediate,” he said. The same amount of aluminum given in a vaccine would not produce as high of a blood concentration as the same amount given intravenously, he said, and the aluminum would be eliminated over time as it was “absorbed from the non-intravenous administration site.”

“Bottom line: Any time after the administration by the non-intravenous routes the blood level of aluminum would be less than after the intravenous route,” Yokel said.

Studies of Aluminum Adjuvants Are Ongoing

Online posts and articles also misleadingly imply that there aren’t studies into the safety of aluminum in vaccines. As we’ve said, people have studied the safety of aluminum in vaccines in the past and continue to do so.

One recent post included a screenshot of an Informed Consent Action Network webpage that says, “CDC and NIH unable to provide a single study to support the safety of injecting aluminum adjuvants despite its widespread use in childhood vaccines.” ICAN — a nonprofit founded by Del Bigtree, who has a history of spreading incorrect information about vaccines — describes making Freedom of Information Act requests to the Centers for Disease Control and Prevention and the National Institutes of Health for “any human or animal studies” that the agencies relied on to “establish the safety of injecting infants and children” with aluminum adjuvants.

It is true that the agencies did not send studies back in response to specific FOIA requests, but this does not mean aluminum adjuvants have not been studied.

According to documents on the ICAN website, the CDC’s Immunization Safety Office ultimately responded that “[t]his request is outside of ISO purview and should be referred to the U.S. Food and Drug Administration.” The NIH told ICAN to search publicly available materials, such as the scientific literature.

The FDA assesses the safety of vaccines on a case-by-case basis. This includes evaluating whether the included adjuvants adversely affect the safety of the vaccine. 

Outside of the FDA approval process, there also have been attempts to evaluate various safety concerns related to aluminum adjuvants. One 2004 study, published in the Lancet Infectious Diseases, responded to concerns about aluminum-containing versions of diphtheria, tetanus and pertussis, or DTP, vaccines by pooling data from studies in children that compared DTP vaccines with and without aluminum adjuvants.

“The results of our review should be interpreted within the limited quantity and quality of available evidence,” the researchers said. “Within these limits, we found no evidence that aluminum salts cause any serious or long-lasting adverse events.”

Another concern was that aluminum in vaccines might cause a family of autoimmune disorders, but this has not been borne out. The evidence doesn’t support the notion that these conditions are caused by aluminum adjuvants, according to a 2017 review article published in the Journal of Allergy and Clinical Immunology: In Practice. 

For instance, the researchers said, one large study found that people who received allergy shots containing a very high cumulative dose of aluminum — used outside the U.S. — had a lower rate of autoimmune disease than those who received other allergy treatments.

Most recently, a study published in 2022 in Academic Pediatrics found a “potential safety signal” indicating an association between aluminum-containing vaccines and asthma. The study relied on medical records from Vaccine Safety Datalink, a vaccine safety monitoring collaboration between the CDC and health care organizations.

The researchers chose to study asthma because of animal data indicating a theoretical immunological mechanism by which aluminum-containing vaccines could increase asthma risk while also decreasing the risk of autoimmune diseases, such as Type 1 diabetes. Interestingly, a separate VSD study, published in 2021 in Pediatrics, found that increased aluminum exposure via vaccines was associated with a reduced risk of Type 1 diabetes.

Sometimes potential safety signals turn out to be real, and sometimes they do not. The question of whether aluminum-containing vaccines are linked to asthma “is now undergoing further evaluation and more studies to try to determine if it’s really true or whether it’s just an association,” meaning there is no cause-and-effect relationship, Halsey said.