From a comprehensive study:

"Vaccines often contain preservatives , adjuvants, additives, or manufacturing residuals in addition to pathogen-specific immunogens. Some parents, alerted by stories in the news media or information contained on the World Wide Web, are concerned that some of the substances contained in vaccines might harm their children. We reviewed data on thimerosal, aluminum, gelatin, human serum albumin, formaldehyde, Antibiotics , egg proteins, and yeast proteins. Both gelatin and egg proteins are contained in vaccines in quantities sufficient to induce rare instances of severe, immediate-type hypersensitivity reactions. However, quantities of mercury, aluminum, formaldehyde, human serum albumin, Antibiotics , and yeast proteins in vaccines have not been found to be harmful in humans or experimental animals."


http://pediatrics.aappublications.org/cgi/content/full/112/6/1394


You could take most any food, shampoo or household products on the market today and print off a list of components, including additives and trace elements which would be comparable to the list for vaccines. Yet there's no concerted effort to frighten people into not eating, washing their hair or cleaning their houses.

Any substance, including water, is harmful in large enough doses. Extremely tiny quantities of virtually any substance are harmless (if this wasn't true, homeopaths would be killers). :)

What antivaxers do is try to hype parents' fears about harmless components and rare side effects of vaccines, while ignoring the far greater risk of serious illness, complications and death due to diseases that are preventable through vaccination.