Robert F. Kennedy Jr’s vaccine advisers are now discussing the safety, already widely confirmed, of vaccines containing aluminum salts.

The latest target of the committee of experts chosen by Robert Francis Kennedy Jr, Trump’s health secretary, is a substance crucial to the effectiveness of vaccines. On Friday, December 5, newly appointed Centers for Disease Control and Prevention (CDC) scientist advisors met to discuss the safety of aluminum salts, used in some vaccines to boost the immune response. Many immunology experts see this move by Kennedy Jr, known for his skeptical positions on vaccines, as an attempt to influence and rewrite the CDC’s recommendations on pediatric vaccinations.

Aluminum salts: what they are and where they are found

Small amounts of some aluminum salts (aluminum hydroxide, aluminum phosphate, potassium, and aluminum sulfate) are added to vaccines to strengthen the immune system’s response to antigens, the pathogen fragments introduced by vaccines to stimulate the production of antibodies. That is, they are adjuvants (adiuvare in Latin means “to help”): specifically they generate a very low level of inflammation by attracting immune cells near the injection site and making them stay there for a long time.

Aluminum salts are contained in vaccines against diphtheria, tetanus, pertussis, hemophilic influenza type B, hepatitis A, hepatitis B, pneumococcal, meningococcal and papilloma virus, while they are not found in vaccines against measles, mumps, rubella, polio, rotavirus and influenza.

Because you can’t do without adjuvants

Adjuvants such as aluminum salts are an essential element because, without them, vaccines would not be able to stimulate a sufficiently potent response. Thanks to adjuvants such as aluminum salts, less viral material needs to be introduced to trigger a reaction in the body and build long-lasting protection from infection.

As explained above Naturethe use of these substances in vaccines has become even more crucial since we have moved to use fewer and fewer vaccines that contain inactivated pathogens, which can increase the risk of adverse reactions. New generation vaccines contain only some specific components of the pathogens (such as certain viral proteins, or even just the instructions for our body to recreate them), and for this reason, they solicit a more attenuated immune response. This is why the use of adjuvants is essential for the production of a significant quantity of antibodies.

In the future, adjuvants in vaccines (not only aluminum salts but also other substances that enhance the immune response) will play an important role in the production of increasingly sophisticated vaccines – such as the one against the HIV virus, which to work will have to stimulate antibodies that bind to many different variants of this transformative virus.

Are aluminum salts in vaccines safe?

Yes: their safety has been attested by rigorous and large-scale scientific studies: one of the most recent and important is dated 15 July 2025, and had the aim of “evaluating the association between cumulative exposure to aluminum resulting from vaccination in early childhood and the risk of autoimmune, atopic or allergic disorders and neurological development”. Kennedy has, for example, repeatedly suggested that aluminum salts in vaccines are linked to food allergies, while other members of the anti-vax movement argue that they increase the risk of some neurodevelopmental disorders, such as autism (again).

The study, which lasted 24 years and covered 1.2 million Danish children, concluded that there are no links between aluminum salts in vaccines and any of the 50 chronic disorders (autoimmune, neurodevelopmental, allergic) evaluated. Kennedy requested that it be withdrawn, the scientific journal, Annals of Internal Medicinehe refused.

All vaccines containing these and other adjuvants undergo thorough safety studies before regulators, such as the FDA, can approve them. Aluminum salts have been used in vaccines for over 90 years, during which hundreds of millions of people have been vaccinated and protected from potentially very serious diseases. The maximum adverse reactions they gave were pain and swelling at the injection site, which disappeared after a day or two.

There is also a question of dosage to consider: as highlighted on the blog Vaccinate…YESa child who undergoes all the recommended vaccinations in the first year of life is exposed to a quantity of aluminum salts equal to a few thousandths of a gram. We human beings ingest small quantities of aluminum continuously, mainly through food (contaminated for example by packaging) and water, but also through deodorants, make-up, sunscreens: according to the FDA, the main source of exposure to aluminum remains food and liquids (including breast milk, for the reasons described above).

Returning to vaccines…

According to Marco Cavaleri, head of the department for public health threats at the EMA, the European Medicines Agency, any formal request to eliminate aluminum from vaccines would be a shock to the system, because it would make life-saving vaccinations ineffective. “You can’t just get rid of an adjuvant that works and is safe before you’ve found something else that you’re sure will be a good replacement,” Cavaleri commented.