“…Occasionally, immunization can precipitate the development of autoimmune diseases directed against normal tissues (e.g., Guillain-Barre' syndrome) (3). In addition to the agents themselves, vaccine production within cells or complex artificial media may allow for the induction of severe allergic reactions to foreign proteins incorporated in the vaccine preparation (4). Bacterial vaccines can also have undesirable side effects: certain pertussis vaccines cause some very severe complications in children (e.g., vomiting, anorexia, convulsions, pain, fever) because of endotoxins present in the vaccine (5) while the widely used BCG vaccine for tuberculosis has been shown to cause a number of adverse reactions, including local abscesses at the site of injection, lymphadenitis, pulmonary lesions and even bone lesions (6).…”