MHLU - Health Status Resource

Adverse Events Following Immunization (AEFI)

An adverse event following immunization (AEFI) is an unfavourable medical condition or reaction that occurs after an immunization is given.  An adverse event that follows an immunization may or may not be due to that immunization.  Reports of AEFIs from Middlesex-London are compiled and assessed as part of the provincial, national and international system of vaccine safety monitoring.