You are here Home Glossary of technical terms Glossary of technical terms adverse event following immunisation Listen Print Share Twitter Facebook Email An unwanted medical reaction after administration of a vaccine, which may or may not be related to the vaccine. Adverse events may be at the site of injection, a general illness or a general allergic reaction. Page history Last updated 11 June 2018 Last reviewed 11 June 2018 Is there anything wrong with this page?