CAEFISS is a voluntary reporting system in which AEFI reports collected by provincial and/or territorial public health authorities are forwarded for collation into the national CAEFI database which is overseen by PHAC�s Vaccine Safety Section within the Surveillance and Outbreak Response Division of the Centre for Immuniaiton and Respiratory Infectious Diseases. While reporting nationally is voluntary, several provinces and territories have laws requiring that health care professionals report AEFI (Ontario, Quebec, Saskatchewan, Manitoba, Nova Scotia, New Brunswick).
The general definition of an AEFI is: any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine. The adverse event may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease. To make a report it is only necessary to have a suspicion that the AEFI may be related to immunization.
In addition to the voluntary reporting system Canada has an active paediatric hospital-based surveillance program known as IMPACT (Immunization Monitoring Program ACTive) for selected serious AEFI. IMPACT is operated through a contract with the Canadian Paediatric Society and includes 12 paediatric centres across Canada which represents over 90% of all paediatric tertiary care admissions in the country. At each centre a nurse monitor and clinical investigator perform active case-finding based on a regular review of admission records. They are assisted by a network which includes admitting department staff, infection control nurses, neurology ward staff and physicians, infectious diseases staff, and medical records technicians.
In 1994, a multidisciplinary group called the Advisory Committee on Causality Assessment (ACCA) was established to review all case reports meeting criteria for severity or "unexpectedness". This group is composed of specialists in pediatrics, public health, epidemiology, infectious diseases, immunology, neurology and adverse event surveillance. The committee usually meets for two days annually and also conducts telephone conferences as needed to review selected cases. Cases that are reviewed are stripped of all identifiers and distributed to each member in advance. Selection criteria for case review include neurological AEFI such as meningitis/encephalitis, encephalopathy and febrile seizures requiring hospitalization; AEFI resulting in a fatal outcome or permanent disability and other AEFI requiring hospitalization. Each case is reviewed using the WHO-UMC (World Health Organization-Uppsala Monitoring Centre) causality assessment criteria of Very Likely, Probable, Possible, Unlikely, Unrelated, or Unclassifiable to determine whether the adverse event was related to the administration of the vaccine(s).