With all the information available on vaccines, it can be hard to separate fact from fiction. Here's the truth behind some of the most common misconceptions about vaccines.
Do vaccines cause autism?
No. Scientists have studied this for years, in large groups of children, and have found no evidence that there is any link between vaccines and autism. There is also no link between thimerosal (a preservative found in the influenza vaccine but not in any other children's vaccines) and autism. The original study that suggested a link between vaccines (in particular, the measles, mumps, and rubella vaccine) and autism was found to be flawed and incorrect. There were so many problems with this study that the journal that originally published it has retracted it (taken it back).
Do vaccines cause autoimmune disorders or SIDS?
No. You may have heard that vaccines can cause autoimmune disorders (conditions where the immune system attacks the body, such as type 1 diabetes and multiple sclerosis). This is not true. Scientists have done many large studies and have found no evidence that vaccines cause autoimmune disorders.
Vaccines also do not cause SIDS (sudden infant death syndrome). This myth started when people noticed that some infants who died of SIDS had recently been immunized with the diphtheria, tetanus, pertussis vaccine. But it turns out that this was nothing more than a coincidence: SIDS happens in the same age group when the vaccine is usually given, so it would be normal to see some SIDS deaths occur after the vaccine purely due to chance. But the two are completely unrelated: the vaccine did not cause the SIDS deaths - these would have happened regardless of whether the vaccine was given. A number of good-quality studies have confirmed that vaccines do not cause SIDS.
Does giving multiple vaccines overload the immune system?
No. Children often receive more than one immunization at the same health care professional's visit. As a parent, you may wonder whether all the antigens (parts of dead or weakened viruses or bacteria) are just too much for your child's tiny immune system to handle. But the truth is, the antigens from vaccines are just a drop in the bucket compared to the huge number of germs your child is exposed to every day. For example, the vaccines given at your child's 2-month visit contain 34 antigens, but your child is exposed to millions of germs every day. The amount of antigens in vaccines doesn't come close to overwhelming your child's immune system. In fact, the opposite is true - the antigens in these vaccines are helping your child's immune system learn to fight new infections. And having multiple vaccines at the same visit means fewer health care professional's visits, which can save you time and also be less traumatic for your child.
Do vaccines contain toxic ingredients?
No. Vaccine ingredients are carefully evaluated and checked for safety. Let's take a closer look at a few ingredients you may have heard about:
- Thimerosal is added to some vaccines as a preservative. Because thimerosal contains mercury, a panel of researchers investigated whether the levels of mercury in childhood vaccines could damage the nervous system. They found no evidence that these small amounts of mercury caused any nervous system damage in children. The only children's vaccinations that contain thimerosal are some flu vaccines.
- Aluminum is used in some vaccines to produce a stronger response from the immune system so that the vaccine can contain a smaller amount of killed or weakened germs. Aluminum occurs naturally and is found in air, water, and food. The amount of aluminum in vaccines is no more than the amount found in breast milk and baby formula.
- Formaldehyde helps with vaccine manufacturing. It is used to inactivate certain viruses and toxins. Vaccines contain only a tiny "trace" amount of formaldehyde because most of it is removed when the vaccine is purified during the manufacturing process. The amount in vaccines is much smaller (less than one-tenth the amount) than the amount found naturally in the typical baby's body.The formaldehyde in vaccines is only a concern for people who are allergic to it.