What are the adjuvants for RNA vaccines?

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.