Aluminum is one of the many vaccine ingredients that have come under fire from the Health and Human Services secretary Robert F. Kennedy Jr. and vaccine skeptics, who have suggested the substance can cause a range of childhood diseases. But a new study is the latest to refute those claims, finding no link between vaccines containing aluminum and health problems in kids.
The research, published July 15 in Annals of Internal Medicine, followed more than one million Danish children over a 24-year period and found no evidence that aluminum-containing vaccines increased the risk of allergic, autoimmune, or neurodevelopmental disorders.
“It’s the largest and most comprehensive study to date of the safety of aluminum-adjuvanted childhood vaccines,” says the study coauthor Anders Hviid, a doctor of medical science, a professor, and the head of the epidemiology research department at Statens Serum Institut in Copenhagen, Denmark.
An adjuvant is an ingredient added to a vaccine to boost the body’s immune response. Adjuvants help vaccines prompt stronger and longer-lasting protection against disease.
“We expect this will be a landmark study on the safety of aluminum-adjuvanted childhood vaccines,” he adds.
Why Do Some Vaccines Contain Aluminum?
Aluminum has been used as a vaccine adjuvant for humans since 1932.
“Some vaccines aren’t going to be effective enough unless you receive an adjuvant that enhances the immune response,” says Paul Offit, MD, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia, who wasn’t involved in the study.
Aluminum adjuvants are found in vaccines that protect against:
These vaccines have all been approved by the U.S. Food and Drug Administration (FDA) after undergoing rigorous evaluation for safety and effectiveness.
The amount of aluminum in vaccines is “trivial,” Dr. Offit says, typically less than 1 milligram (mg) per dose.
Still, Dr. Hviid says it’s “understandable that parents can be anxious about vaccine safety with the many fear-based narratives circulating today.”
He says he hopes the new study contributes “solid scientific evidence” to help parents make the best health decisions for their children.
Study Found ‘No Associations’ Between Aluminum in Vaccines and Chronic Health Conditions
The new study wanted to assess the connection, if any, between cumulative aluminum exposure from vaccinations before age 2 and a child’s subsequent risk for autoimmune, atopic, allergic, and neurodevelopmental disorders.
Researchers began with data from a nationwide registry on childhood vaccinations in Denmark. The study included more than 1.2 million children born between 1997 and 2018, who were split roughly 50-50 between boys and girls.
The registry tracked the children between ages 2 and 5, or until they were no longer available for follow-up. The data included information on vaccines received before age 2 and any subsequent health diagnoses.
Just 1.2 percent of the children did not receive any aluminum-containing vaccines before age 2.
Because vaccine recommendations and availability varied throughout the study period, the researchers were able to compare health outcomes among children who received different amounts of aluminum exposure from vaccines.
For kids in the study, the aluminum content per vaccine dose ranged from 0.125 to 1 mg of aluminum. The total vaccine-related aluminum exposure was 3 mg on average by age 2.
During the follow-up, researchers looked for 50 vaccine-related adverse health effects, including:
Their analysis found no associations between cumulative aluminum exposure via vaccines and the development of one of the chronic conditions, or any increased risk for those conditions.
“For many of the outcomes, our results are quite precise, and we can exclude even small increases in risk with certainty,” Hviid says.
Offit — one of the inventors of the rotavirus vaccine and an internationally recognized expert in virology and immunology — calls it a “superb study” that offers “reassuring” evidence that vaccines with aluminum are safe.
What Are the Limitations of This Study?
The study was observational, meaning there was no randomized placebo control group, the gold-standard of clinical trials. “It’s not ethically feasible or logistically possible to conduct clinical trials to evaluate these associations,” Hviid says.
It wouldn’t be ethical to give some children real vaccines and give ineffective dummy vaccines to others. Instead, “We have to rely on high-quality observational research such as our study,” Hviid explains.
While researchers factored in socioeconomic status, Hviid says they could not “exclude small differences in the comparison groups that we have not been able to control for.”
The study looked at just 50 specific health conditions, he says, which means the results don’t rule out possible connections to other conditions.
Findings Reiterate the Safety of Aluminum in Vaccines
Secretary Kennedy has reportedly asked a government advisory group to reexamine many of the aluminum-containing vaccines that have been used for almost a century.
Aluminum-adjuvanted vaccines are the “backbone of immunization programs worldwide,” Hviid says, and there’s no replacement. Not administering these vaccines would result in death and large-scale disease.
“A lot of the misinformation about childhood vaccines tends to revolve around vaccine ingredients,” he says, and the aluminum in vaccines is in “minuscule doses” and isn’t comparable to aluminum in metal form.
Offit adds that, every day, people are exposed to aluminum, which is the third most abundant element on earth. He says he hopes the new study will help dispel many of the myths surrounding aluminum in vaccines.
Hviid is hopeful that “our study and its message will have a wide reach. The more parents, clinicians, and policymakers these reassuring results reach, the better.”
EDITORIAL SOURCES
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Resources
Rosenbluth T. Yes, Some Vaccines Contain Aluminum. That’s a Good Thing. New York Times. January 24, 2025.
Andersson NW et al. Aluminum-Adsorbed Vaccines and Chronic Diseases in Childhood: A Nationwide Cohort Study. Annals of Internal Medicine. July 14, 2025.
Emily Kay Votruba has copyedited and fact-checked for national magazines, websites, and books since 1997, including Self, GQ, Gourmet, Golf Magazine,Outside, Cornell University Press, Penguin Random House, and Harper's Magazine. Her projects have included cookbooks (Padma Lakshmi's Tangy Tart Hot & Sweet), self-help and advice titles (Mika Brzezinski's Know Your Value: Women, Money, and Getting What You're Worth), memoirs (Larry King's My Remarkable Journey), and science (Now You See It: How the Brain Science of Attention Will Transform How We Live, Work, and Learn, by Cathy Davidson). She started freelancing for Everyday Health in 2016.
Erica Sweeney has been a journalist for more than two decades. These days, she mostly covers health and wellness as a freelance writer. Her work regularly appears in The New York Times, Men’s Health, HuffPost, Self, and many other publications. She has a master’s degree in journalism from the University of Arkansas at Little Rock, where she previously worked in local media and still lives.
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