Basics and Common Questions:
Ingredients of Vaccines - Fact Sheet
Chemicals commonly used in the production of vaccines include a suspending fluid (sterile water, saline, or fluids containing protein); preservatives and stabilizers (for example, albumin, phenols, and glycine); and adjuvants or enhancers that help improve the vaccine's effectiveness. Vaccines also may contain very small amounts of the culture material used to grow the virus or bacteria used in the vaccine, such as chicken egg protein.
- Millions of doses of vaccines are administered to children in this country each year. Ensuring that those vaccines are potent, sterile, and safe requires the addition of minute amounts of chemical additives.
- Chemicals are added to vaccines during manufacturing to inactivate viruses or bacteria and to stabilize the vaccine, help to preserve it from losing its potency over time.
- The amount of chemical additives found in vaccines is very small.
- All routinely recommended pediatric vaccines manufactured for the U.S. market are available in formulations that contain no thimerosal or only trace amounts.
- Vaccine ingredients sorted by vaccine [50KB / 3 pages]
U.S. Vaccine excipients (inactive substance used as a carrier for the active ingredients of a medication) and media summary, part 2 from the "Pink Book"
Additives used in the production of vaccines may include
- suspending fluid (e.g. sterile water, saline, or fluids containing protein);
- preservatives and stabilizers to help the vaccine remain unchanged (e.g. albumin, phenols, and glycine); and
- adjuvants or enhancers to help the vaccine to be more effective.
Common substances found in vaccines include:
- Aluminum gels or salts of aluminum which are added as adjuvants to help the vaccine stimulate a better response. Adjuvants help promote an earlier, more potent response, and more persistent immune response to the vaccine.
See also: "Aluminum in Vaccines: What you should know" [ 579KB / 2 pages] Also available in Spanish [579KB / 2 pages]
- Antibiotics which are added to some vaccines to prevent the growth of germs (bacteria) during production and storage of the vaccine. No vaccine produced in the United States contains penicillin.
- Egg protein is found in yellow fever and most influenza vaccines, which are prepared using chicken eggs. Ordinarily, persons who are able to eat eggs or egg products safely can receive these vaccines.
- Formaldehyde is used to inactivate bacterial products for toxoid vaccines (these are vaccines that use an inactive bacterial toxin to produce immunity). It is also used to kill unwanted viruses and bacteria that might contaminate the vaccine during production. Formaldehyde is removed from the vaccine before it is packaged, leaving only a trace.
- Monosodium glutamate (MSG) and 2-phenoxy-ethanol which are used as stabilizers in a few vaccines to help the vaccine remain unchanged when exposed to heat, light, acidity, or humidity.
- Thimerosal is a mercury-containing preservative that is added to vials of vaccine containing more than one dose to prevent contamination and growth of potentially harmful bacteria.
For children with a prior history of allergic reactions to any of these substances in vaccines, parents should consult their child’s healthcare provider before vaccination.
- To find out what chemical additives are in specific vaccines, ask your healthcare provider or pharmacist for a copy of the vaccine package insert, which lists all ingredients in the vaccine and discusses any known adverse reactions.
- To ensure the safety of vaccines, the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), the National Institutes of Health (NIH), and other Federal agencies routinely monitor and conduct research to examine any new evidence that would suggest possible problems with the safety of vaccines. To keep abreast of the latest information, continue to reference these materials.
- To report a health problem that followed vaccination you or your provider should call the Vaccine Adverse Event Reporting System (VAERS) at 1-800-822-7967.
- Vaccine Ingredients: What you should know [817KB / 2 pages]
Some parents are concerned about ingredients contained in vaccines, specifically aluminum, mercury, gelatin, and antibiotics. However, parents can be reassured that ingredients in vaccines are minuscule and necessary.
- Common Ingredients in U.S. Licensed Vaccines
Prior to licensure, as part of FDA’s review, FDA takes all the ingredients into account, including the active ingredients as well as other substances. After FDA approves a vaccine, FDA and CDC continuously monitor its safety.
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Content last reviewed on January 1, 2014
Content Source: National Center for Immunization and Respiratory Diseases