According to the CDC, on-time vaccination throughout childhood is imperative because it helps provide immunity before children are exposed to potentially life-threatening diseases. Vaccines are tested to ensure that they are safe and effective for children to receive at the recommended ages. 

Some people are concerned about vaccines being linked to the occurrence of autism in people. The studies have shown that there is no link between receiving vaccines and being autistic. In 2011, an Institute of Medicine (IOM) report, on 8 vaccines given to children and adults with rare exceptions, these vaccines are very safe. 

 

A study conducted by the CDC in 2013 added to the research showing that vaccines do not cause autism. They looked at the number of antigens from vaccines during the first two years of life. The results showed that the total number of antigens from vaccines received was the same between autistic children and typical children. 

 

One vaccine ingredient that had been studied specifically was thimerosal. It is a mercury-based preservative. It is used to prevent contamination of multidose vials of vaccines. The research shows that thimerosal does not cause autism. A 2004 scientific review by the IOM concluded that “the evidence favors rejection of a causal relationship between thimerosal-containing

 vaccines and autism.”They found no link between the MMR vaccine and autism. This substance was removed between 1999 and 2001 to calm the hysteria. There is a trace amount in some flu vaccines. There are thimerosal-free options for people who do not want it in their vaccines. 

 

Aluminum is the third most abundant element in the environment, and the most abundant metal, and is found diffusely in soil, water, plants, and air. It is found in a variety of consumer products, as well as throughout the human food chain, and in many pharmaceuticals. In vaccines, aluminum is used as an adjuvant, a component that boosts immune response to the vaccine antigens. When adjuvants are used, they allow for smaller amounts of vaccine to be given, as well as fewer doses. Aluminum has been used in a variety of vaccines, including hepatitis A and B, H. influenzae type b, and pneumococcal vaccines.

As a vaccine component, aluminum has been extensively tested for safety as part of pre-licensure clinical trials. We know from studies examining the aluminum exposure of infants that the cumulative amount of aluminum from vaccines in the first 6 months of life is actually far less than that received from dietary sources, including both breast milk and formula . Both sources represent far less exposure than that represented by a regulatory minimal risk level (MRL), which is established by the Agency for Toxic Substances and Disease Registry. The safety of aluminum salts from vaccines, and from other sources, has also been established in studies examining blood and hair levels of aluminum in infants, and associated neurodevelopmental outcomes . Such studies have not proven a link between blood and hair concentrations of aluminum and receipt of vaccines, nor between blood and hair aluminum concentrations and neurodevelopmental outcomes.

Mercury

Mercury, or more specifically a compound containing ethylmercury called thimerosal, has been used at various points in the past as a preservative in multidose vials of vaccine. Because some forms of mercury are known to be neurotoxic, this has led to concerns in the past that this mercury-containing compound could represent a danger to patient safety. However, the form of mercury contained in thimerosal (ethylmercury) is substantially different from the more toxic methylmercury, despite the similarity in their names. Ethylmercury is cleared quickly from human tissues, and does not accumulate substantially, unlike methylmercury. When the safety of thimerosal as a vaccine component has been examined, it has not been found to have any associated risks, including no evidence of an increased risk of autism.