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Safety & Prevention

Q. What ingredients are in vaccines?


Antigen forms include:

  • Partial bacteria. are made up of the specific part of the dead bacteria that will prompt a protective immune response. Some vaccines are made this way including the Hib, pneumococcal, meningococcal, diphtheria, tetanus and pertussis (whooping cough) vaccines. 



Q. Are these other ingredients in vaccines safe?

A. Yes.

Q. Why are these other ingredients in vaccines? 



Q. Do vaccines contain antifreeze?

A: No. Antifreeze is typically made of ethylene glycol, which is unsafe. Confusion has arisen, because polyethylene glycol (a chemical used in antifreeze and personal care products like skin creams and toothpaste) is used in vaccines and is safe. It is used to inactivate the influenza virus in some influenza vaccines. It is also used to purify other vaccines.

Q. Do vaccines contain mercury?

A: Almost all childhood vaccines do NOT contain any mercury. Methylmercury, which is found in fish and other animals (including humans) can be toxic and lead to adverse effects in humans. Thimerosal, a mercury-based preservative, was removed from most childhood vaccines in 2001. Thimerosal contains a different form of mercury called ethylmercury, which is processed by the body very differently than methylmercury, and is not associated with the same adverse effects. It is still present in some influenza vaccines. Thimerosal is still used in the manufacture of some vaccines to prevent contamination. The thimerosal is removed at the end of the manufacturing process. In some cases, a tiny amount of thimerosal remains. The remaining amount is so small, that it is not possible for it to have any effect. Valid scientific studies have shown there is no link between thimerosal and autism. In fact, autism rates have actually increased since thimerosal was removed from childhood vaccines. The American Academy of Pediatrics (AAP), the American Medical Association (AMA), the CDC, and the Institute of Medicine (IOM) agree that science does not support a link between thimerosal in vaccines and autism. For the IOM report, go to

Q. Do vaccines contain fetal tissue?

A. No. A few vaccines involve growing the viruses in human cell culture. Two cell lines provide the cultures needed for producing vaccines. These lines were developed from two fetuses in the 1960s. The fetuses were aborted for medical reasons, not for the purpose of producing vaccines. These cell lines have an indefinite life span, meaning that no new aborted fetuses are ever used. No fetal tissue is included in the vaccines, either, so children are not injected with any part of an aborted fetus.

Q. Should vaccines be “greener”?

A. The amount of each additive used in vaccines is very small. In fact, we are exposed to much higher levels of these chemicals in our everyday lives. In vaccines, these ingredients are used to make the vaccine safer and more effective. Each vaccine is tested many times to make sure it is safe and works. Taking ingredients out might affect the ability of the vaccine to protect a child. Research is always being done to make sure that ingredients in vaccines continue to be the safest and best available for children.


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Questions and Answers About Vaccine Ingredients (Copyright © 2013 American Academy of Pediatrics)