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Adjuvants are used in vaccine production to accelerate, prolong, or enhance antigen-specific immune responses. They help to raise an early, long-lasting and efficient immune response to the vaccine. This increases vaccine efficacy and provides a high degree of protection from the disease against which you are vaccinating.

Adjuvants can help to reach the same level of immune protection with fewer injections or a lower dose than when vaccinating with the non-adjuvanted antigen alone. 

Doctor giving a senior woman a vaccination.
How do adjuvants increase vaccine efficacy?

An adjuvant is a substance which is added to a vaccine to increase its efficiency. The word adjuvant has its origin from the Latin “adjuvare” which means “to help”. From a chemical point of view, adjuvants are a highly heterogenous group of compounds that share only one functional characteristic: that of being able to enhance immune responses. Adjuvants improve the presentation of antigens, resulting in a stronger immune response and the production of memory cells.  

There are still challenges with existing vaccines regarding providing sufficient immunogenicity; adjuvants can help with this as well as antigen sparing. The improved immune response in the presence of an adjuvant means less antigen is required in the formulation. This has many benefits, including:

  • Reducing adverse reactions at the injection site without impacting the strength of the immune response
  • Requiring fewer injections of the vaccine
  • Decreasing formulation cost and speeding up vaccine production 

Although adjuvants can be classified according to the type of immunity they best stimulate, this becomes problematic because most adjuvants activate both humoral and cell-mediated immunity. Only the extent of stimulation varies with different adjuvants. Furthermore, the antigen with which the adjuvant is mixed may also influence the outcome of the immunisation. Finally, adjuvants can be classified according to the Toll-like receptors they may interact with. 

The most commonly used adjuvants are: mineral-based adjuvants (aluminium hydroxides and aluminium phosphates), oil emulsions and purified extracts from the Quillaja Saponaria Molina tree. Croda has manufactured adjuvants for human and veterinary vaccines since 1939 and is the only company to manufacture sterile mineral-based adjuvants using an aseptic process.

Immunisation in developing countries 

There are long geographical distances between the vaccinating physician and the population. Valuable resources can be saved if protection can be achieved using two injections instead of three. Precision vaccines targeted at vulnerable populations are also of increasing importance.

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Addressing the challenges of vaccine formulation

2022 Adjuvants Brochure
12.5 MB
vaccine development

Adjuvant Systems

For more than 80 years Croda has been dedicated to safe and effective adjuvants suitable for use in both human and veterinary vaccines.

Closeup of cattle veterinarian's hand in white medical rubber glove holding syringe with medicine or vaccine for dairy cows on livestock farm

Livestock vaccination

In the case of vaccinating cattle that must be brought in from ample pastures, or other animals being kept in the open over large distances, just the resources needed for bringing the animals for vaccination may be cost prohibitive. Adjuvants can help by requiring fewer vaccine doses. 

Eliciting a strong immune response in the mother animal may also help the survival of the offspring, as they receive maternal antibodies from weaning, at a time when their own immune system is not yet fully developed.
Learn more about the work we do in veterinary vaccines
Vaccine of tomorrow

Vaccines of tomorrow

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View our range of vaccine adjuvants



Well-established as a common component in a variety of vaccines, Adju-Phos is an aluminium-based adjuvant that induces strong Th2 immune responses.



One of the most widely used vaccine adjuvants, Alhydrogel is an aluminium-based adjuvant used in clinically-approved vaccines that can elicit effective Th2 immune responses.



AlhydroVet is an aluminium hydroxide gel product specifically manufactured for use as an adjuvant in veterinary vaccines.



A versatile immunostimulatory saponin that’s widely used as a potent veterinary adjuvant, Quil-A can work against both intra- and extra-cellular pathogens, stimulating innate and Th-mediated adaptive...

QS 21

QS 21

*sample can be ordered for investigational use only* A powerful immunostimulatory saponin that acts as a potent vaccine adjuvant, QS 21 can stimulate both cell-mediated (Th1) and humoral (Th2) immune...

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