Small amounts of aluminum have been used as an adjuvant in vaccines for many decades. But despite a long-standing safety record, vaccination critics continue to make alleged connections between the adjuvant and numerous health problems such as autism, asthma or diabetes. A large meta-study has now re-examined these claims and included the latest studies on possible side effects of the vaccines. The result: There is no evidence of causal connections between vaccines containing aluminum and negative health effects such as autism and the like.
Aluminum salts are the most important adjuvants in vaccines worldwide. Tiny amounts of these additives strengthen the immune response to inactivated vaccines and in this way ensure that the vaccinations work better and protect for longer. They are used, among other things, in vaccines against diphtheria, tetanus, whooping cough, hepatitis, HPV and meningitis – some for almost a hundred years. Depending on the vaccine, a vaccine dose now typically contains between 0.125 and 0.82 milligrams of aluminum – significantly less than we absorb from other sources, including drinking water, food and deodorants containing aluminum. For comparison: a single ten-gram piece of chocolate can contain one milligram of aluminum.
Review based on new evidence
Nevertheless, these vaccine additives do not have a good reputation: “Despite decades of post-approval monitoring, questions continue to arise in scientific circles and among the public about the possible long-term effects of vaccines with aluminum adjuvants,” writes a team led by Pamela Doyon-Plourde from the Canadian Public Health Agency. Among other things, US Secretary of Health and anti-vaxxer Robert F. Kennedy Junior regularly repeats unsubstantiated claims that link aluminum-containing vaccines to numerous negative health consequences such as autism, asthma and diabetes.
To test these claims against the latest available scientific evidence, Doyon-Plourde and her team conducted a comprehensive meta-study, evaluating 59 studies published through the end of 2025. In addition to numerous smaller case series, these included eleven randomized controlled studies and nine cohort studies, including a Danish study published in 2025 with more than 1.2 million children.
No evidence of serious side effects
The result supports the current state of knowledge: “High-quality evidence from randomized controlled trials and large cohorts consistently showed no connection between aluminum-containing vaccines and serious or long-term health consequences such as asthma, autism spectrum disorders or other chronic diseases,” the researchers report. The team also found no evidence of a connection to vaccinations containing aluminum for ADHD and diabetes. Randomized controlled studies showed that vaccination reactions such as headaches and muscle pain were no more common after vaccinations containing aluminum than after vaccinations without aluminum.
However, the researchers found a possible connection for small hardenings at the puncture site. However, these were mainly described in case series that only included a few test subjects, so the team believes there is a high risk of bias. Such hardenings have been observed in rare cases after the diphtheria-tetanus-pertussis vaccination and after the hepatitis B vaccination. Even if, according to reports, they sometimes persisted for several months, they usually disappeared on their own.
“Current evidence does not support a causal relationship between aluminum-containing vaccines and serious or long-term health consequences,” conclude Doyon-Plourde and her team. “These results are consistent with the broader post-approval safety evidence base supporting the continued use of aluminum-containing vaccines in vaccination programs.”
Source: Pamela Doyon-Plourde (Public Health Agency of Canada, Ottawa) et al., BMJ, doi: 10.1136/bmj-2025-088921