An adjuvant is classically defined as “an ingredient of a vaccine that helps create a stronger immune response in the patient’s body.”
Adjuvants in Vaccines
The oldest and most commonly used adjuvant in vaccines in the United States is aluminum.

Why use adjuvants?
Because it often helps you use fewer antigens in the vaccine, leading to less side effects.
Aluminum is used in many vaccines, including DTaP, hepatitis A, hepatitis B, Hib, HPV, pneumococcal, and Tdap vaccines.
Monophosphoryl lipid A (ASO4) is another adjuvant that is used in one brand of HPV vaccine, Cervarix, which is no longer available in the United States.
Other vaccine adjuvants include:
- MF59 – an oil-in-water emulsion of squalene oil that is used in one version of the Fluad influenza vaccine that is only approved for adults who are at least 65 years old.
- AS01B – a liposomal formulation of monophosphoryl lipid A (MPL) and QS-21, a natural compound extracted from the Chilean soapbark tree, which is used in Shingrix.
- CpG 1018 – a synthetic form of DNA, cytosine phosphoguanine (CpG), that mimics bacterial and viral genetic material, and is used in Heplisav-B, a hepatitis B vaccine for adults.
Not all vaccines have adjuvants though.
Vaccines without adjuvants include:
- ActHIB
- Varivax for chickenpox
- live zoster (Zostavax)
- measles, mumps & rubella (MMR)
- meningococcal vaccines (Menactra, Menveo)
- rotavirus vaccines
- seasonal flu (except adjuvated Fluad)
- inactivated polio (IPOL)
- yellow fever vaccine
And keep in mind that other countries use different adjuvants.
The Bottom Line on Vaccine Adjuvants
Adjuvants in vaccines are safe.
More on Vaccine Adjuvants
- Are There Hidden Ingredients in Vaccines?
- Adjuvant 65 in Vaccines and the Peanut Allergy Epidemic
- How Aluminum Became the New Thimerosal
- Fact Checking What Kids Receive When They Are Vaccinated
- Unavoidably Unsafe Vaccines
- Squalene in Vaccines
- Talking about Vaccines: Adjuvants and Ingredients
- Vaccine Ingredients – Aluminum
- CDC – Vaccine Adjuvants Concerns
- Aluminum adjuvant in vaccines – let’s go cherry picking
- Demystifying Vaccine Ingredients – Aluminum
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