Vaccine Ingredients
Vaccine Ingredients

Vaccines contain antigens that prompt the body to create antibodies. The antibodies fight the germs that cause the disease the vaccine is intended to prevent. In addition to antigens, vaccines contain other ingredients or additives used in the production process. These additional ingredients are used to purify, stabilize and preserve, increase the effectiveness of the vaccines, and/or create the vaccine.

Vaccine ingredients include
  • Suspending fluid - the liquid that contains the chemicals used during production that kill or weaken the germ for use in vaccines.
  • Preservatives and stabilizers - substances that ensure the vaccine content and potency remain unchanged.
    Common preservatives and stabilizers include:
    1. Thimerosal, a preservative used in multiple-dose vials to prevent bacterial growth in vaccine vials.
    2. Formaldehyde, a stabilizer that kills or inactivates unwanted germs in vaccines.
    3. Monosodium glutamate (MSG), a stabilizer that protects vaccines from heat, light, humidity or acidity while they are stored.
    4. Gelatin, a stabilizer that protects vaccines from heat while they are stored.
  • Adjuvants - substances used to enhance the effectiveness of the vaccines. Aluminum is the only adjuvant approved for use in US licensed vaccines.
  • Residual materials - the materials used to grow the virus or bacteria contained within the vaccine.
    Common residual materials include:
    1. Antibiotics which are used during the production of some vaccines to prevent bacterial growth. The residual amount after production is also useful to prevent bacterial growth while the vaccine is stored.
    2. Egg protein which is present in nfluenza and yellow fever vaccines because chicken eggs are used in the production of theses vaccines.

Complete listings of vaccine components specific to each vaccine are available at: Institute of Vaccine Safety, Johns Hopkins University