Common Misconceptions about Vaccines

​​​Vaccines are the most effective way to keep children healthy — a fact supported by decades of scientific research. Still, common vaccine misconceptions can confuse parents.

You already have a trusted resource for vaccine information. The same pediatrician who prescribes your child's medications and tracks their growth can answer your questions about routine vaccines.

Read on for facts behind common vaccine myths, plus trusted resources to help you make informed decisions.

What should parents know about vaccine side effects?

Most vaccine side effects are minor and temporary. These side effects can include a low-grade fever (100-101°F) and redness, warmth and swelling at the injection site (lasting less than 24 hours). Febrile seizures are rare — at most 30 in 100,000 children — and are typically harmless.

Side effects not associated with vaccines include: 

• Infertility — There is no known association between vaccines and fertility problems in women or men.
• Cancer — There is no evidence that vaccines cause cancer, but there is evidence that some vaccines — such as HPV — prevent cancers.
• Diabetes — Studies have found that vaccines are not associated with an increased risk of diabetes.
• Changes in DNA — Vaccines do not enter your DNA or change your cells. They work in the cell cytoplasm, not the nucleus where DNA is stored.

Are vaccine ingredients like aluminum and thimerosal safe for children?

These metals have not been found to pose a risk to vaccine recipients. 

A very small amount of aluminum is used in some vaccines as an adjuvant during the development process. This helps boost the immune response so fewer doses are needed. Aluminum is also found naturally in common foods, such as fruits, cereal, baby formula and drinking water.

A very small amount of thimerosal — a mercury-based preservative — was used to prevent the growth of germs in vaccines. It is not used in single-dose vaccines routinely recommended for children.

Do vaccines cause autism?

Vaccines do not cause autism. Research now shows that autism likely begins before birth and may be influenced by infections and genetic and environmental factors.

The misconception that vaccines cause autism originated with a study published in 1998 by Andrew Wakefield. It suggested a connection between autism and the measles, mumps and rubella (MMR) vaccine. The study involved only 12 children and was immediately rebutted and fully retracted due to ethical violations and flawed methodology. A second Wakefield paper was found to be critically flawed and he lost his medical license.

Large, high-quality studies show no connection between vaccines and autism. For example, a Danish study published in 2019 of more than 537,000 children found no connection between the MMR vaccine and autism.

Where can parents find credible vaccine information?

This article provided vaccine facts about some misconceptions, but there are many more. If you have questions or concerns, the best place to start is your pediatrician. In addition, these reliable resources can be found online:

• HealthyChildren.org — American Academy of Pediatrics (AAP)
• CHOP.edu/vaccine-education-center — Children's Hospital of Philadelphia (CHOP)

The AAP and CHOP are endorsed by global health authorities and provide up-to-date, peer-reviewed information. By relying on trusted sources, you can make confident decisions about your child's health. 

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