FA16 Immunization Module’s Updates

Adjuvants in vaccine formulations

Adjuvants (from Latin, meaning to help) aid in the immune response to vaccines.  It has been found that pure antigen only mounts weak responses. Surprisingly, it is the imperfect antigen solution – those with leftover impurities or added adjuvants – that mount the strongest responses from the innate and adaptive immune systems.  As Dr. Tapping mentions in the podcast lecture on vaccination, adjuvants “increase the danger” of the antigen solution.  Often, it is substances that are pro-inflammatory and somewhat toxic that aid in the response to antigen.

Aluminum compounds are the only adjuvants licensed in United States.  The bulk of these compounds are termed alum.  Alum activates the intracellular inflammation pathway in macrophages and dendritic cells, leading to production of IL-1β.  IL-1β goes on to exert effects leading to local inflammation. Other common adjuvants in other parts in the world include various lipid products and bacterial components (have toxic effects, however).

As stated, adjuvants, through the production of proinflammatory molecules like IL-1β are responsible for the local inflammation response.  This response is often what is referred to as the minor adverse reaction to vaccines.  Pain, swelling, and redness at the site of injection are the most common reactions and occur with up to 80% of vaccine doses.

Aside from simply increasing the efficacy of vaccines, the use of adjuvants has the added benefit of reducing the necessary amounts of antigen (a product of the increased efficacy).  This allows stocks of antigen to stretch further and reduces the possibility of vaccine shortages.

Sources:

CDC, "General Rules of Immunization"

Dr. Tapping's lecture slides

  • Gage Winger
  • Kylie Mena
  • Richard Tapping
  • Carly Gridley