A massive study just published in Annals of Internal Medicine has put to rest one of the more persistent fears about childhood vaccines.

Over the years there has been mounting concern that the tiny amounts of aluminum contained in many childhood vaccines might contribute to chronic health conditions.

Drawing on Denmark's national health records spanning 24 years, from 1997 to 2018, a Danish research team analyzed data from more than 1.2 million children. They tracked cumulative aluminum exposure from vaccines administered to kids before the age of two, checking to see if there was any link to 50 chronic disorders, including 36 autoimmune disorders such as juvenile arthritis, nine allergy or asthma conditions, and five neurodevelopmental disorders like autism and ADHD.

It's understandable how even a whisper of potential harm from vaccines can trigger anxiety in parents. If you're one of them, you can now rest assured.

No link between aluminum and these conditions was found. In fact, for key outcomes, particularly neurodevelopmental disorders like autism and ADHD, the data suggest a modestly lower risk for vaccinated children, though researchers caution this isn't evidence of a protective effect. Simply put, there's no meaningful link between aluminum in vaccines and chronic childhood illnesses.

The study contradicts Health and Human Services Secretary Robert F. Kennedy, Jr, who has spread vaccine misinformation for years. Specifically, Kennedy said on a podcast in 2024 that aluminum in vaccines is “extremely neurotoxic.”

“Our study addresses many of these concerns and provides clear and robust evidence for the safety of childhood vaccines,” the study's senior author, Anders Hviid, a professor and the head of epidemiology research at Statens Serum Institut, a sector of the Danish Ministry of Health that focuses on combatting and preventing infectious diseases, said in a media release. “This is evidence that parents need to make the best choices for the health of their children.”

The study's far-reaching analysis took advantage of “natural variation” in how many vaccines with aluminum the Danish kids received. Some received fewer shots in their early years because of shifting national guidelines. The researchers assessed aluminum exposure in milligrams by age two and then compared health outcomes up to age five or eight. The team used rigorous statistical methods, adjusting for factors like sex, birth cohort, follow up time, breastfeeding and socioeconomic status.

This was an observational study. This means 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 explained. To have a control group would have meant that some children were denied vaccinations.

The result? No link to chronic disease. That's not speculation based on and promoted through fear; it's a scientific finding based on the best available evidence.

Aluminum salts have been used in non-live vaccines since the 1930s. They are commonly included in shots that protect against diphtheria, tetanus, pertussis, as well as polio, among others. This study stands as the largest and most comprehensive to date and offers high-quality observational data that counter misinformation.

It's understandable how even a whisper of potential harm from vaccines can trigger anxiety in parents. If you're one of them and still wondering whether the aluminum in today's childhood vaccines might contribute to autism, ADHD, asthma, allergies or a host of autoimmune diseases, you can now rest assured. According to this Danish study, there is no evidence of risk. The quantities of aluminum that are injected through a vaccine are miniscule and do not appear to harm developing systems.

The Danish analysis offers one of the most statistically powerful answers to fears around aluminum in vaccines. The result? No link to chronic disease. That's not speculation based on and promoted through fear; it's a scientific finding based on the best available evidence.