You are here Home Glossary of technical terms Glossary of technical terms allergy Listen Print Share Twitter Facebook Email An immune response to a foreign substance that is harmless in most people. The foreign substance could be a food, medicine or vaccine component Page history Last updated 11 June 2018 Last reviewed 11 June 2018 Is there anything wrong with this page? Help us improve the Australian Immunisation Handbook What you were doing? (required) What went wrong? (required) Leave this field blank