Vaccine Ingredients
Other topics related to Parents: Making the Vaccine Decision
Vaccines contain ingredients, called antigens, which cause the body to develop immunity. Vaccines also contain very small amounts of other ingredients--all of which play necessary roles either in making the vaccine, or in ensuring that the vaccine is safe and effective. These types of ingredients are listed below.
Type of Ingredient | Examples | Purpose |
---|---|---|
Preservatives | Thimerosal (only in multi-dose vials of flu vaccine) | To prevent contamination |
Adjuvants | Aluminum salts | To help stimulate the body’s response to the antigens |
Stabilizers | Sugars, gelatin | To keep the vaccine potent during transportation and storage |
Residual cell culture materials | Egg protein | To grow enough of the virus or bacteria to make the vaccine |
Residual inactivating ingredients | Formaldehyde | To kill viruses or inactivate toxins during the manufacturing process |
Residual antibiotics | Penicillin, sulfa drugs | To prevent contamination by bacteria during the vaccine manufacturing process |
Today, except for some flu vaccines, none of the childhood vaccines used routinely in the United States contain mercury (thimerosal) as a preservative. Although no evidence suggests that there are safety concerns with thimerosal, vaccine manufacturers stopped using it as a precautionary measure. Now it is contained in very tiny amounts only in multi-dose vials of flu vaccine. Thimerosal is necessary in vaccines that come in multi-dose vials because they require that each individual vaccine dose be drawn from the vial with a new needle and syringe. With each needle inserted, there is the potential for introducing microbes into the vial.
There is no evidence of harm caused by the small amounts of thimerosal in flu vaccines, except for minor reactions like redness and swelling at the injection site. Flu vaccines that do not contain thimerosal are available.
Images and logos on this website which are trademarked/copyrighted or used with permission of the trademark/copyright or logo holder are not in the public domain. These images and logos have been licensed for or used with permission in the materials provided on this website. The materials in the form presented on this website may be used without seeking further permission. Any other use of trademarked/copyrighted images or logos requires permission from the trademark/copyright holder...more
This graphic notice means that you are leaving an HHS Web site. For more information, please see the Exit Notification and Disclaimer policy.
Contact Us:
- Centers for Disease Control and Prevention
1600 Clifton Rd
Atlanta, GA 30333 - 800-CDC-INFO
(800-232-4636)
TTY: (888) 232-6348 - New Hours of Operation
8am-8pm ET/Monday-Friday
Closed Holidays - cdcinfo@cdc.gov