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What are the adjuvants for RNA vaccines?

Text updated on 2021-02-17

Pfizer and ModeRNA RNA vaccines contain no adjuvants!

The basic concept of vaccination is to effectively stimulate the immune response to a foreign body.Immunogenicity is used to define the ability of the vaccine to induce an immune response. In some cases, immunogenicity is not high enough. To strengthen it, adjuvants are then added to the active ingredient of the vaccine. Adjuvants, such as aluminium or substances derived from saponins (natural soaps), are molecules added to the composition of the vaccine to stimulate the inflammatory response, thereby increasing the immunogenicity of the vaccine. The potential toxicity of adjuvants and their potential role in the occurrence of more or less serious adverse events following vaccination is a point that may cause hesitation about vaccination.

The active ingredient in Pfizer and Moderna vaccines is RNA. The good news is that unlike inactivated and recombinant protein vaccines, which sometimes need an adjuvant, RNA vaccines do not. RNA and the nanoparticles (very small particles) containing RNA are already immunogenic enough to induce an effective immune response. Therefore, there is no need to add an adjuvant to enhance the immune response.

Messenger RNA vaccines are composed of RNA and lipid nanoparticles (fat particles) that surround and protect the RNA, allowing it to enter human cells. These vaccines also contain sterile water, sucrose for viscosity, a buffer solution to maintain pH, and salts.

Similarly, AstraZeneca's recombinant adenovirus vaccine does not contain adjuvants.

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List of compounds in the ModeRNA vaccine

Annex I summary of product characteristics - Vaccine Moderna

List of compounds of the ModeRNA vaccine in French

Vidal - COVID-19 ModeRNA vaccine

List of Pfizer BioNTech Vaccine Compounds

Annex I summary of product characteristics - Pfizer BioNTech

List of AstraZeneca Oxford vaccine compounds

Annex I summary of product characteristics - AstraZeneca Oxford

A history of adjuvant development.

Pasquale, A. D., Preiss, S., Silva, F. T. D., & Garçon, N. (2015). Vaccine adjuvants: from 1920 to 2015 and beyond. Vaccines, 3(2), 320-343.

Discussion on adjuvants in vaccines, current knowledge, issues and perspectives.

Gupta, R. K., & Siber, G. R. (1995). Adjuvants for human vaccines-current status, problems and future prospects. Vaccine, 13(14), 1263-1276.

RNA vaccines are highly immunogenic.

Karikó, K., Buckstein, M., Ni, H., & Weissman, D. (2005). Suppression of RNA recognition by Toll-like receptors: the impact of nucleoside modification and the evolutionary origin of RNA. Immunity, 23(2), 165-175.

Further reading

What are the different types of COVID-19 vaccines?

Are RNA vaccines a miracle of science?

Are adverse vaccine reactions expected?