Vaccines are made up of antigens. Antigens are small amounts of the bacteria or virus that stimulate the immune system to create antibodies that prevent future infections. Vaccines also contain some additional ingredients, and each has a specific function. These ingredients have been studied and are safe for humans in the amount used in vaccines. This amount is much less than children encounter in their environment, food and water.

Sometimes a child may be sensitive to one of the components of a vaccine, and an allergic reaction may result. For this reason, you should discuss any allergies your child may have with your health care provider.

A very small group of very vocal, but misinformed, individuals have made accusations regarding the safety of vaccines, claiming that vaccines contain a laundry list of toxins. In many instances these allegations are completely incorrect. In others, the claims are taken out of context.

Vaccines may include:

  • Preservatives: Preservatives help keep the vaccine vials from getting contaminated with germs. Since 1968 the United States Code of Federal Regulations (the CFR) has required, in general, the addition of a preservative to multi-dose vials of vaccines; and worldwide, preservatives are routinely added to multi-dose vials of vaccine. Tragic consequences have followed the use of multi-dose vials that did not contain a preservative (including deaths) and have served as the driving force for this requirement.

  • Thimerosal: Thimerosal is a commonly known preservative that was at the center of controversy a few years ago. Thimerosal, which is an ethylmercury-based preservative, was removed from vaccines in the U.S. in the late 1990s in an effort to reduce the overall burden of mercury from all sources. Unlike the methylmercury found in the environment, ethylmercury quickly leaves the body. Numerous studies have shown that autism rates are no lower in children who received vaccines without thimerosal than those who received thimerosal-containing vaccines. Measles, mumps, and rubella (MMR) vaccines do not and never did contain thimerosal. Varicella (chickenpox), inactivated polio (IPV), and pneumococcal conjugate vaccines have also never contained thimerosal. Influenza (flu) vaccines are currently available in both thimerosal-containing (for multi-dose vaccine vials) and thimerosal-free versions. The thimerosal in multi-dose vials is necessary because each time an individual dose is drawn from a multi-dose vial with a new needle and syringe, there is the potential to contaminate the vial with harmful microbes (toxins). For a complete list of vaccines and their thimerosal content level, see the U.S. Food and Drug Administration (FDA) Thimerosal in Vaccines page

  • Formaldehyde: Formaldehyde is used to kill viruses or inactivate toxins during the manufacturing process of vaccines. Formaldehyde is present in the environment and is a byproduct of metabolism so it is already present in the human body.

  • Adjuvants: Aluminum salts are an adjuvant that have been used in some vaccines for over 75 years to improve the vaccine's performance by helping to stimulate the body's immune system to produce antibodies. Without the use of an adjuvant, we would need to administer more shots in a vaccine series or face lower immunity and less protection from the disease. Aluminum is also commonly found in food, water, infant formula and even breast milk.

  • Egg Protein: Some vaccines are prepared in eggs which means that some egg proteins are present in the final vaccine product. The egg proteins help manufacturers to grow enough of the virus or bacteria needed to make the vaccine. Eggs are used in the production of the MMR (measles, mumps, rubella) vaccine. The American Academy of Pediatrics (AAP) indicates that the MMR vaccine can be safely given to all patients with egg allergy. Scientific evidence supports the routine use of one-dose administration to those with egg allergy, including patients with a history of severe, generalize anaphylactic reactions to egg. Egg protein is also present in small amounts in the influenza (flu) vaccines. According to the American Academy of Allergy, Asthma & Immunology (AAAAI) the flu vaccine can be safely administered to those with egg allergies. Their statement regarding flu vaccines is: "Studies show that flu vaccines can be safely administered to egg allergic individuals, whether in the primary care provider's office or allergist's office depending on the severity of the allergic reaction to eating eggs." If you or your child are allergic to eggs, make sure to tell your doctor or healthcare provider before getting vaccinated.

  • Gelatin:Some vaccines contain gelatin to protect them against freeze-drying or heat. People with severe allergies to gelatin should talk to their doctor or healthcare provider before getting vaccinated.

  • Antifreeze: You may have heard that vaccines contain products such as antifreeze and other outrageous components. This is not true. Antifreeze typically contains ethylene glycol, an unsafe and highly toxic (poisonous) component, or propylene glycol, a safer and less toxic option to ethylene glycol. Neither of these members of the glycol family of compounds is used in vaccines. In vaccines, polyethylene glycol is used to inactivate the virus in some influenza vaccines and is also used to purify other vaccines. Polyethylene glycol is approved by the FDA and considered non-toxic for medical and other uses.* It is used in a variety of products including skin cream, toothpaste, lubricating eye drops, laxatives, and as an anti-foaming agent in food. It is also used as an irrigating solution in surgical procedures.

* Victor O. Sheftel (2000). Indirect Food Additives and Polymers: Migration and Toxicology. CRC, 1114-1116.

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