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Vaccines contain an active component (antigen) which induces an immune response. The antigen is a modified or partial form of the virus, bacteria or the toxin that causes the disease against which the vaccine protects. The vaccine antigen is altered from its original form so it can longer cause the disease but produce an immune response. Vaccines may also contain additional components such as preservatives, additives, adjuvant and traces of other components.
Preservatives are used to prevent fungal and/or bacterial contamination of vaccines, and are present in some but not all vaccines.
Additives are used as stabilisers and help maintain a vaccine’s effectiveness by keeping the antigen and other vaccine components stable during storage.
An adjuvant is a substance included in vaccine formulation to enhance the immune-stimulating properties of a vaccine.
Trace components are the remaining minute quantities of substances that have been used in the early stages of the production process of individual vaccines. Depending on the manufacturing process used this may include trace amounts of cell culture fluids, egg proteins, yeast, antibiotics or inactivating agents. Usually, only minute traces of these substances are detected in the final vaccine product.
The Medical Journal of Australia published a study titled
“Vaccine components and constituent: responding to consumer concerns”
produced by Barbara E Eldred, Angela J Dean, Treasure M McGuire and Allan L Nash; from the Education and Information Unit, Mater Pharmacy Services, Mater Misericordiae Hospital, South Brisbane, QLD
The study describes the key constituents present in vaccines, discusses issues related to safety and acceptability of these constituents, and provides a table highlighting constituents of commercially available vaccines in Australia.
Aluminium is present in several vaccines to improve the immune response.
An average daily exposure of aluminium is about 10-15 mg, most of which comes from foods and water. Humans and other mammals are constantly exposed to aluminium compounds and as a consequence aluminium is found in the blood of all humans and animals. Normally aluminium is excreted through the urine.
Some parents are concerned about aluminium in vaccines to learn more read Aluminum in vaccines what you should know from The education centre at the children’s hospital of Philadelphia or read the Aluminium article from The New Zealand Immunisation Advisory Centre, University of Auckland.
Thiomersal also known as thimerosal, is an organic compound containing 49.6% ethyl mercury by weight. Thiomersal can be used as a preservative in vaccines to prevent fungal and bacterial contamination. In Australia no routine childhood vaccines contain thiomersal. There is a HepB vaccine that contains a traces of yeast proteins and thiomersal (<2ug/ml) which is not routinely used in the childhood immunisation schedule or the school based program. There is no thiomersal in the MMR vaccine. For more information see the NCIRS fact sheet on thiomersal
Page last updated: 23 Sep 2009