Aluminum-based adjuvants in vaccines are safe, contrary to claims based on mouse study

Aluminum salt is a component, also known as an adjuvant, of some vaccines that boosts the immune response to the vaccine’s active ingredient. This helps to give longer-lasting protection against disease. It has been used for nearly a century, and detailed reviews of clinical evidence have not found safety concerns^[1-3].

Despite this, anti-vaccine campaigners regularly question the safety of using aluminum salts in vaccines. In February 2025, a widely shared Facebook reel claimed a study in mice “showed aluminium in vaccines causes cognitive deficits & [is a] possible cause of Parkinson’s & Alzheimer’s disease”. The reel was viewed more than 185,000 times.

This follows a similar pattern of other misleading claims about aluminum in vaccines that Science Feedback previously reviewed (here, here, and here).

As this review will explain, the amount of aluminum present in vaccines is well within safe levels, and a study in mice cannot be extrapolated to humans.

Aluminum levels in vaccines are safe and much lower than aluminum exposure through diet

Some vaccines containing inactivated viruses, such as hepatitis A, hepatitis B, and Hib vaccines, contain aluminum adjuvants to prolong the immune response. This isn’t necessary for live vaccines like the combined measles, mumps, and rubella (MMR) vaccine.

We are all exposed to aluminum through food and the air. By comparison, the amount of aluminum in vaccines is far smaller. Adults ingest seven to nine milligrams of aluminum daily^[3], while vaccines must contain less than 0.85 milligrams per dose.

There is about the same amount of aluminum in a vaccine as there is in a liter of infant formula. An antacid can contain hundreds of times more aluminum than a vaccine dose. Although the body removes ingested and injected aluminum in different ways, one analysis found that 95% of aluminum in the body comes from food^[4].

The metabolism of aluminum in the body can be studied by injecting a rare isotope of aluminum to distinguish it from the aluminum entering the body from other sources, such as diet^[5,6]. The U.S. Food and Drug Administration (FDA) used this information, along with data on the presence of aluminum in diet, to calculate the expected total amount of aluminum in the body for children^[7]. This showed that the total aluminum amount remained within safe levels throughout the first year of life after receiving standard childhood vaccines.

The aluminum in vaccines is insoluble and is held in the muscle before being slowly released into the blood, where most of it is then quickly excreted by the kidneys^[7]. This means that the dosage experienced by the rest of the body remains low and is comparable to that from the diet.

A 2018 review of the evidence on aluminum in vaccines concluded^[8]:

“Analysis of the literature showed that no apparent reason exists to support the elimination of Al from vaccines for fear of neurotoxicity.”

High levels of aluminum are dangerous for health, as has been observed in people receiving kidney dialysis. Patients in the past were exposed to toxic levels of aluminum through dialysis fluids, which their kidneys weren’t able to remove. These extreme cases led to issues in the bones and brain, which haven’t been observed in people receiving minute amounts of aluminum through vaccines^[2,3].

The video was a clip from an anti-vaccine film

The Facebook reel was an excerpt from a 2011 film called “The Greater Good”, which was described as “anti-vaccine propaganda” by David Gorski, a surgical oncologist and managing editor of Science-Based Medicine. The clip features Christopher Shaw, a professor in the Department of Ophthalmology and Visual Sciences, at the University of British Columbia, Canada. In it, Shaw described his study of the effects of aluminum on mice in 2007^[9].

Since the film aired, concerns have been repeatedly raised about Shaw’s research. A similar research study about aluminum in mice by Shaw was retracted in 2017 because “the data and results presented in this paper are clearly not reliable”. CBC News reported that some of the figures had been manipulated and copied from another study. This followed another retraction the year before, which cited “serious concerns regarding the scientific soundness of the article”.

Two other studies by Shaw that claimed aluminum in vaccines was associated with autism were described as “seriously flawed” by the Global Advisory Committee on Vaccine Safety, an independent group of experts that advises the World Health Organisation.

The mouse study cannot be extrapolated to humans

In the 2007 study, Shaw and colleagues studied the impact of the adjuvants aluminum hydroxide and squalene on mice. The researchers hypothesized that these adjuvants in the anthrax vaccine adsorbed (AVA) caused Gulf War illness.

It is important to note that this was a very preliminary study, using only ten mice in the control group. It would be impossible to draw any conclusions about human health from a study like this, given the potential differences in metabolism and physiology with mice^[10]. For instance, rodents show a significant difference from humans in regulating bile acids, which can play an important role in removing aluminum from the body^[11,12].

The study examined the behavior of the mice in the weeks following the injections. The dose of aluminum hydroxide given to the mice was 100 micrograms per kilogram, compared to about 68 micrograms per kilogram that humans would receive in two doses of the AVA vaccine.

One experiment suggested that the mice given aluminum alone had a 50% fall in muscle strength and endurance. This effect was not seen for mice given squalene alone nor aluminum combined with squalene.

Such an extreme impact on muscle strength has not been observed in aluminum and vaccine safety studies. This profound side effect would be easily identified given that aluminum-based adjuvants are so widely used. This result clearly demonstrates how this mouse experiment cannot be extrapolated to humans.

The mice were also studied in a cognitive test called a water maze. This is where mice are tested on their ability to remember where a hidden platform is in a pool. The mice were divided into four groups—control, aluminum, squalene, and aluminum plus squalene. Each group was tested at five time points after the injections.

The mice given either aluminum or squalene injections performed the same as the control group. Mice given both aluminum and squalene performed worse on the week 24 test, having performed the same as the other groups for the preceding four tests. No further tests were carried out beyond this point to determine if this was a real, ongoing effect. Further, squalene and aluminum adjuvants are not used together in vaccines, so it is not clear how this is relevant to vaccine safety in humans.

The mice were given the vaccine subcutaneously, i.e. just under the skin. This matched how the anthrax vaccine was given to humans at the time of the study. However, the anthrax vaccine was an outlier and all other aluminum-containing vaccines are given intramuscularly, i.e. into the muscle^[13]. After a clinical trial published in 2008, the FDA recommended the anthrax vaccine is given intramuscularly when used preventatively pre-exposure^[14]. This further reduces the applicability of the study to understanding the effect of vaccines in humans.

Conclusion

The mouse study cited in the Facebook reel was very preliminary and the results cannot be extrapolated to human health without further research.

Vaccine safety is closely monitored by national and international health authorities. After billions of doses of aluminum-containing vaccines, the evidence still leads to the conclusion that low doses of aluminum are safe. We are exposed to far more aluminum through diet, and vaccines make no significant difference to the amount of aluminum in our bodies.

REFERENCES

• 1 – McKee and Marrack (2017) Old and new adjuvants. Current Opinion in Immunology.
• 2 – Jefferson et al. (2004) Adverse events after immunisation with aluminium-containing DTP vaccines: systematic review of the evidence. The Lancet Infectious Diseases.
• 3 – Movsas et al. (2013) Effect of Routine Vaccination on Aluminum and Essential Element Levels in Preterm Infants. JAMA Pediatrics.
• 4 – Goullé and Grangeot-Keros. (2020) Aluminum and vaccines: Current state of knowledge. Médecine et Maladies Infectieuses.
• 5 – Priest. (2004) The biological behaviour and bioavailability of aluminium in man, with special reference to studies employing aluminium-26 as a tracer: review and study update. Journal of Environmental Monitoring.
• 6 – Priest et al. (1995) Human metabolism of aluminium-26 and gallium-67 injected as citrates. Human & Experimental Toxicology.
• 7 – Mitkus et al. (2011) Updated aluminum pharmacokinetics following infant exposures through diet and vaccination. Vaccine.
• 8 – Principi and Esposito. (2018) Aluminum in vaccines: Does it create a safety problem? Vaccine.
• 9 – Petrik et al. (2007) Aluminum adjuvant linked to gulf war illness induces motor neuron death in mice. NeuroMolecular Medicine.
• 10 – Perlman. (2016) Mouse models of human disease: An evolutionary perspective. Evolution, Medicine & Public Health.
• 11 – Straniero et al. (2020) Of mice and men: murine bile acids explain species differences in the regulation of bile acid and cholesterol metabolism. Journal of Lipid Research.
• 12 – Sutherland et al. (1996) Bile is an important route of elimination of ingested aluminum by conscious male Sprague-Dawley rats. Toxicology.
• 13 – Pittman (2002) Aluminum-containing vaccine associated adverse events: role of route of administration and gender. Vaccine.
• 14 – Marano et al. (2008) Effects of a Reduced Dose Schedule and Intramuscular Administration of Anthrax Vaccine Adsorbed on Immunogenicity and Safety at 7 Months. JAMA.