What’s Happening with Aluminum?

Likely you’ve heard some back-and-forth recently about the use of aluminum as an adjuvant in vaccines. Here’s what you need to know from both sides of the argument:

Aluminum in Vaccines

• Aluminum is used in vaccines as an adjuvant to boost the immune response to the vaccine. Aluminum adjuvants are found in many, but not all, routinely recommended vaccines. It is not used in live attenuated virus vaccines like MMR, rotavirus, or varicella vaccines.
• Aluminum adjuvants are aluminum salts, not elemental aluminum.
• The amount of aluminum given to an infant through vaccines is very small—about 4.4 mg in the first 6 months of life. As aluminum is the third most abundant element on earth, children are constantly ingesting aluminum through their diet (including through infant formula and breast milk). CHOP’s vaccine education center has a table on how much aluminum is contained in each vaccine.
• Both the National Vaccine Program Office and the Global Advisory Committee on Vaccine Safety have reviewed studies on the aluminum content in vaccines. Each found no reason to make changes in vaccine recommendations based on the use of aluminum adjuvants.

The Denmark Study

• On July 15, 2025, Niklas Andersson and others published a nationwide cohort study on the association between aluminum adjuvants and chronic diseases in childhood. The study was published in a respected and peer-reviewed journal, Annals of Internal Medicine, and examined the medical records of over 1.2 million children born in Denmark between 1997 and 2018. The study looked at incident events of 50 chronic disorders versus the cumulative aluminum received through vaccination during the first 2 years of life. Records were analyzed from age 2 through 5 years, with some analyzed through age 8 years if additional analysis was needed.
• The study looked at aluminum exposure by milligram, comparing children who received vaccines and had low aluminum exposure to those who received vaccines and had high aluminum exposure (range 0-4.5 mg). No difference in outcomes was found, regardless of the cumulative aluminum exposure.
• The study concluded there was no increase in incidence of any of the 50 chronic conditions (neurodevelopmental, autoimmune, allergic disorder, etc.) because of increased aluminum exposure from vaccines.

The Critics

• The study excluded children who died before age 2 or who were diagnosed with chronic conditions prior to age 2: Correct. Children born with serious congenital conditions or who have heart disease, liver failure, etc., that was diagnosed before age 2 were unlikely to have completed the vaccination series or to have their conditions because of aluminum in vaccines.
• The study excluded children with records indicating abnormally high aluminum exposures: Correct. These were thought to be spurious and due to coding anomalies or duplicated records.
• The analysis adjusted for the number of medical visits in the first 2 years of life: Correct. If this was not done, some conditions would be diagnosed based on more frequent interactions with the medical system rather than because of their exposure to aluminum.
• The study did not look at vaccinated versus unvaccinated: Correct. This study is more important as it looked at the dose-response relationship between aluminum exposure and the development of chronic disease. It showed that there was no increase in incidence of those diseases between those who had low exposures versus children who had high exposures.
• A figure in the supplemental materials found a hazard ratio for Asperger syndrome per milligram of aluminum of 1.67, indicating those with aluminum exposure had a higher risk of developing Asperger syndrome (now classified as part of Autism Spectrum Disorder): Correct. But the confidence interval was 1.01 to 2.77 and the case number was very small—51 cases out of more than 1.2M children. This mild increase in risk was only seen in the group of children born between 2007 and 2018 and was not seen when researchers extended the follow up from age 5 years to age 8 years, nor was it seen in the analysis of the full cohort.
• Denmark’s childhood immunization schedule is different from that of the U.S. and has fewer vaccinations: Correct. But the range of aluminum exposure in this analysis was 0-4.5 mg, which would include similar exposures as in the U.S.
• Three authors work at an institute that produces vaccines used in Denmark. Correct. But conflicts were disclosed in the publication and reviewed by the journal. Those criticizing the research have conflicts as well, as they are involved in lawsuits against vaccine manufacturers.
• The reference for the information above can be found here.

The Bottom Line

• This study looked at the aluminum exposure from vaccines for every child in Denmark born between 1997 and 2018—more than 1.2M children.
• The total aluminum dose from vaccines received by age 2 ranged from 0-4.5 mg, with most children receiving between 2-4 mg. The median exposure among children in the U.S. is 3 mg.
• There was no association between aluminum dose and the development of any of 50 chronic conditions, including autism.