Common Vaccine Misperceptions and Concerns Explained

There are misperceptions about risks and side effects of vaccination, and because there are so many false reports in the media, this section aims to clear up any confusion.

Common vaccine side effects ( include mild reactions like fever, or swelling or soreness at the injection site. These reactions indicate that the vaccine is working. Very rarely, you might have a serious side effect, such as an allergic reaction. Only one in 1 million children vaccinated experience this side effect. There is absolutely no sound evidence suggesting that vaccines cause or trigger autism. Decades of research around the world prove vaccinations are safe and effective. Meanwhile, the effects of an infectious disease can be severe and long-lasting, including brain damage or even death. Bottom line: The bigger risk is in delaying a vaccination, because the longer you wait to vaccinate your child, the longer he or she is risking exposure to a serious and potentially life-altering disease.

Some parents worry about overloading a child's immune system. But parents don't need to be concerned about this. The American Academy of Pediatrics says that babies' immune systems can handle the number of recommended vaccines ( according to the vaccination schedule because they are exposed to multiple germs on a daily basis. A healthy baby's immune system can accommodate multiple vaccinations. In fact, babies' immune systems can respond to approximately 100,000 organisms at once. The antigens in vaccines use only a small fraction of a baby's immune system response. Childhood immunizations are recommended to children at a susceptible young age after immunity from their mother wears off. Again, there is more harm in not vaccinating your baby. See:The Harm of Delaying or Skipping.

Another misperception is that vaccinations are unsafe because they contain thimerosal, an organic form of mercury (also called ethylmercury) that prevents vaccines from being contaminated. This form of mercury is completely different from methylmercury, which can damage the nervous system. Although thimerosal has been shown to be safe, now all routine childhood vaccines are available in thimerosal-free forms, including the seasonal flu vaccine.

Also, vaccines do not make a child sick with the disease, and they do not weaken the immune system. Vaccines introduce a killed/disabled antigen into the body so the immune system can produce antibodies against it and create immunity to the disease. That said, it's not uncommon for a child to develop a mild runny nose and/or cough after receiving the flu vaccine. This does not mean, however that your child "got the flu." Also, because it takes about two weeks for the flu vaccine to become effective, and because flu symptoms do not immediately appear, a person could unknowingly already be infected with the flu when receiving a vaccination. Someone in this situation might assume that the flu vaccine gave them the flu, but this is not possible or true.

Finally, the most common and most concerning misperception is that vaccines cause autism. But there is absolutely no sound proof of this. To read more, visit The Truth About Autism.

Vaccines are developed with the highest safety standards in mind. The Food and Drug Administration, along with the Centers for Disease Control and Prevention, developed the Vaccine Adverse Events Reporting System ( to maintain these high standards.

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