From the Centers for Disease Control and Prevention (CDC):
Additives used in the production of vaccines may include:
1. Suspending fluid (e.g. sterile water, saline, or fluids containing protein);
2. Preservatives and stablilizers to help the vaccine remain unchanged (e.g. albumin, phenols, and glycine)
3. Adjuvants or enhancers that help the vaccine improve its work.
Common substances found in vaccines include:
Aluminium gels or salts of aluminium …added as adjuvants to help the vaccine stimulate production of antibodies to fight off diseases and aid other substances in their action. In vaccines, adjuvants may be added to help promote an earlier response, more potent response, or more persistent immune response to disease.
Antibiotics…added to vaccines to prevent the growth of germs (bacteria) in vaccine cultures.
Egg protein…found in vaccines prepared using chick embryos. Ordinarily, persons who are able to eat eggs or egg products safely can receive these vaccines.
Formaldehyde…used to inactivate bacterial products for toxoid vaccines. It is also used to kill unwanted viruses and bacteria that might be found in cultures used to produce vaccines.
Monosodium glutamate (MSG) and 2-phenoxy-ethanol…used as stabilizers in a few vaccines to help the vaccine remain unchanged even in the presence of forces such as heat, light, acidity, humidity etc. MSG is also found in many foods, especially Asian foods and flavor enhancers.
Thimerosal…a preservative that might be added to prevent the vaccine from spoiling. Thimerosal is also found in some contact lens solutions and throat sprays.” •”For children with a prior history of allergic reactions to any of these substances in vaccines, parents should consult their child’s health care provider before vaccination.
To find out what chemical additives are in specific vaccines, ask your health care provider or pharmacist for a copy of the vaccine package insert, which lists all ingredients in the vaccine and discusses any known “adverse reactions.”
According to the CDC, “with the exception of some influenza vaccine, none of the vaccines used to protect preschool children against 12 infectious diseases contain thimerosal as a preservative. (Those with a concentration of less than 0.0002% contain what is considered “trace,” or insignificant, amounts.) Certain Influenza (flu) vaccines and tetanus-diphtheria vaccines (Td) given to children age 7 and older contain thimerosal as a preservative.”
If you want to know more from the CDC about thimerosal-free vaccines, it’s found at Availability of Thimerosal-free Vaccines. Also read Thimerosal Content in Some US Licensed Vaccines by The Institute for Vaccine Safety to find out some of the current vaccines that include thimerosal.